ISO 2903-2:2025

ISO metric trapezoidal screw threads — Tolerances — Part 2: Limits of sizes

This document specifies the limits of sizes for major, pitch and minor diameters of ISO metric trapezoidal screw threads (Tr) conforming to ISO 2902 and having basic and design profiles in accordance with ISO 2901. This document is applicable to the metric trapezoidal screw threads with the seven tolerance classes (7H, 8H, 9H, 7e, 8e, 8c and 9c) recommended in ISO 2903.

Filetages métriques trapézoïdaux ISO — Tolérances — Partie 2: Dimensions limites

General Information

• Status: Published
• Publication Date: 24-Jul-2025
• ICS: 17.040.10 - Limits and fits
• ICS: 21.040.10 - Metric screw threads
• Technical Committee: ISO/TC 1 - Screw threads
• Drafting Committee: ISO/TC 1 - Screw threads
• Current Stage: 6060 - International Standard published
• Start Date: 25-Jul-2025
• Due Date: 22-Aug-2025
• Completion Date: 25-Jul-2025

Relations

• Revises: ISO 2903:2016 - ISO metric trapezoidal screw threads — Tolerances
• Effective Date: 13-Apr-2024

Standards Content (Sample)

International
Standard
ISO 2903-2
First edition
ISO metric trapezoidal screw
2025-07
threads — Tolerances —
Part 2:
Limits of sizes
Filetages métriques trapézoïdaux ISO — Tolérances —
Partie 2: Dimensions limites
Reference number
© ISO 2025
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Limits of sizes . 1
4.1 General .1
4.2 Internal threads.2
4.3 External threads .14
Bibliography .31

iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 1, Screw threads.
A list of all parts in the ISO 2903 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iv
International Standard ISO 2903-2:2025(en)
ISO metric trapezoidal screw threads — Tolerances —
Part 2:
Limits of sizes
1 Scope
This document specifies the limits of sizes for major, pitch and minor diameters of ISO metric trapezoidal
screw threads (Tr) conforming to ISO 2902 and having basic and design profiles in accordance with ISO 2901.
This document is applicable to the metric trapezoidal screw threads with the seven tolerance classes (7H,
8H, 9H, 7e, 8e, 8c and 9c) recommended in ISO 2903.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 2903, ISO metric trapezoidal screw threads — Tolerances
ISO 5408, Screw threads — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 5408 apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Limits of sizes
4.1 General
The limits of sizes specified shall be derived from the fundamental deviations and tolerances specified in
ISO 2903.
The limits of sizes for major, pitch and minor diameters of screw threads (Tr) have been calculated by the
following formulae and rounded to the third decimal place.

Internal thread
Major diameter D = D + 2 a
4 min c
Pitch diameter D = D = D – 0,5 P
2 min 2
D = D + T
2 max 2 min D2
Minor diameter D = D = D – P
1 min 1
D = D + T
1 max 1 min D1
External thread
Major diameter d = d
max
d = d – T
min d
Pitch diameter d = d + es = d – 0,5 P + es
2 max 2
d = d – T
2 min 2 max d2
Minor diameter d = d – 2 a = d – P – 2 a
3 max 1 c c
d = d – T
3 min 3 max d3
Where es is a negative value.
For the symbols and their definitions see ISO 2903.
The maximum major diameter of internal thread D is not specified.
4 max
For the seven tolerance classes and nominal diameter ranges see Table 1.
Table 1 — Tr screw threads with the seven recommended tolerance classes
Nominal diameter
Screw thread Tolerance class Table number
mm
7H Table 2
From 8 to 300
Internal thread 8H Table 3
9H From 8 to 100 Table 4
7e Table 5
8e From 8 to 300 Table 6
External thread
8c Table 7
9c From 8 to 100 Table 8
4.2 Internal threads
Limits of sizes for the internal threads with tolerance class 7H shall be as specified in Table 2.

Table 2 — Limits of sizes for the internal threads with tolerance class 7H
Dimensions in millimetres
Major
Nominal
Pitch diameter Minor diameter
diameter
diameter Pitch
D P D D D D D
4 min 2 max 2 min 1 max 1 min
8 1,5 8,300 7,474 7,250 6,690 6,500
9 1,5 9,300 8,474 8,250 7,690 7,500
9 2 9,500 8,250 8,000 7,236 7,000
10 1,5 10,300 9,474 9,250 8,690 8,500
10 2 10,500 9,250 9,000 8,236 8,000
11 2 11,500 10,250 10,000 9,236 9,000
11 3 11,500 9,780 9,500 8,315 8,000
12 2 12,500 11,265 11,000 10,236 10,000
12 3 12,500 10,800 10,500 9,315 9,000
14 2 14,500 13,265 13,000 12,236 12,000
14 3 14,500 12,800 12,500 11,315 11,000
16 2 16,500 15,265 15,000 14,236 14,000
16 4 16,500 14,355 14,000 12,375 12,000
18 2 18,500 17,265 17,000 16,236 16,000
18 4 18,500 16,355 16,000 14,375 14,000
20 2 20,500 19,265 19,000 18,236 18,000
20 4 20,500 18,355 18,000 16,375 16,000
22 3 22,500 20,800 20,500 19,315 19,000
22 5 22,500 19,875 19,500 17,450 17,000
22 8 23,000 18,475 18,000 14,630 14,000
24 3 24,500 22,835 22,500 21,315 21,000
24 5 24,500 21,900 21,500 19,450 19,000
24 8 25,000 20,500 20,000 16,630 16,000
26 3 26,500 24,835 24,500 23,315 23,000
26 5 26,500 23,900 23,500 21,450 21,000
26 8 27,000 22,500 22,000 18,630 18,000
28 3 28,500 26,835 26,500 25,315 25,000
28 5 28,500 25,900 25,500 23,450 23,000
28 8 29,000 24,500 24,000 20,630 20,000
30 3 30,500 28,835 28,500 27,315 27,000
30 6 31,000 27,450 27,000 24,500 24,000
30 10 31,000 25,530 25,000 20,710 20,000
32 3 32,500 30,835 30,500 29,315 29,000
32 6 33,000 29,450 29,000 26,500 26,000
32 10 33,000 27,530 27,000 22,710 22,000
34 3 34,500 32,835 32,500 31,315 31,000
34 6 35,000 31,450 31,000 28,500 28,000
34 10 35,000 29,530 29,000 24,710 24,000
36 3 36,500 34,835 34,500 33,315 33,000
36 6 37,000 33,450 33,000 30,500 30,000
36 10 37,000 31,530 31,000 26,710 26,000

TTabablele 2 2 ((ccoonnttiinnueuedd))
Major
Nominal
Pitch diameter Minor diameter
diameter
diameter Pitch
D P D D D D D
4 min 2 max 2 min 1 max 1 min
38 3 38,500 36,835 36,500 35,315 35,000
38 7 39,000 34,975 34,500 31,560 31,000
38 10 39,000 33,530 33,000 28,710 28,000
40 3 40,500 38,835 38,500 37,315 37,000
40 7 41,000 36,975 36,500 33,560 33,000
40 10 41,000 35,530 35,000 30,710 30,000
42 3 42,500 40,835 40,500 39,315 39,000
42 7 43,000 38,975 38,500 35,560 35,000
42 10 43,000 37,530 37,000 32,710 32,000
44 3 44,500 42,835 42,500 41,315 41,000
44 7 45,000 40,975 40,500 37,560 37,000
44 12 45,000 38,560 38,000 32,800 32,000
46 3 46,500 44,855 44,500 43,315 43,000
46 8 47,000 42,530 42,000 38,630 38,000
46 12 47,000 40,630 40,000 34,800 34,000
48 3 48,500 46,855 46,500 45,315 45,000
48 8 49,000 44,530 44,000 40,630 40,000
48 12 49,000 42,630 42,000 36,800 36,000
50 3 50,500 48,855 48,500 47,315 47,000
50 8 51,000 46,530 46,000 42,630 42,000
50 12 51,000 44,630 44,000 38,800 38,000
52 3 52,500 50,855 50,500 49,315 49,000
52 8 53,000 48,530 48,000 44,630 44,000
52 12 53,000 46,630 46,000 40,800 40,000
55 3 55,500 53,855 53,500 52,315 52,000
55 9 56,000 51,060 50,500 46,670 46,000
55 14 57,000 48,670 48,000 41,900 41,000
60 3 60,500 58,855 58,500 57,315 57,000
60 9 61,000 56,060 55,500 51,670 51,000
60 14 62,000 53,670 53,000 46,900 46,000
65 4 65,500 63,400 63,000 61,375 61,000
65 10 66,000 60,560 60,000 55,710 55,000
65 16 67,000 57,710 57,000 50,000 49,000
70 4 70,500 68,400 68,000 66,375 66,000
70 10 71,000 65,560 65,000 60,710 60,000
70 16 72,000 62,710 62,000 55,000 54,000
75 4 75,500 73,400 73,000 71,375 71,000
75 10 76,000 70,560 70,000 65,710 65,000
75 16 77,000 67,710 67,000 60,000 59,000
80 4 80,500 78,400 78,000 76,375 76,000
80 10 81,000 75,560 75,000 70,710 70,000
80 16 82,000 72,710 72,000 65,000 64,000

TTabablele 2 2 ((ccoonnttiinnueuedd))
Major
Nominal
Pitch diameter Minor diameter
diameter
diameter Pitch
D P D D D D D
4 min 2 max 2 min 1 max 1 min
85 4 85,500 83,400 83,000 81,375 81,000
85 12 86,000 79,630 79,000 73,800 73,000
85 18 87,000 76,750 76,000 68,120 67,000
90 4 90,500 88,400 88,000 86,375 86,000
90 12 91,000 84,630 84,000 78,800 78,000
90 18 92,000 81,750 81,000 73,120 72,000
95 4 95,500 93,425 93,000 91,375 91,000
95 12 96,000 89,670 89,000 83,800 83,000
95 18 97,000 86,800 86,000 78,120 77,000
100 4 100,500 98,425 98,000 96,375 96,000
100 12 101,000 94,670 94,000 88,800 88,000
100 20 102,000 90,800 90,000 81,180 80,000
105 4 105,500 103,425 103,000 101,375 101,000
105 12 106,000 99,670 99,000 93,800 93,000
105 20 107,000 95,800 95,000 86,180 85,000
110 4 110,500 108,425 108,000 106,375 106,000
110 12 111,000 104,670 104,000 98,800 98,000
110 20 112,000 100,800 100,000 91,180 90,000
115 6 116,000 112,500 112,000 109,500 109,000
115 14 117,000 108,710 108,000 101,900 101,000
115 22 117,000 104,850 104,000 94,250 93,000
120 6 121,000 117,500 117,000 114,500 114,000
120 14 122,000 113,710 113,000 106,900 106,000
120 22 122,000 109,850 109,000 99,250 98,000
125 6 126,000 122,500 122,000 119,500 119,000
125 14 127,000 118,710 118,000 111,900 111,000
125 22 127,000 114,850 114,000 104,250 103,000
130 6 131,000 127,500 127,000 124,500 124,000
130 14 132,000 123,710 123,000 116,900 116,000
130 22 132,000 119,850 119,000 109,250 108,000
135 6 136,000 132,500 132,000 129,500 129,000
135 14 137,000 128,710 128,000 121,900 121,000
135 24 137,000 123,900 123,000 112,320 111,000
140 6 141,000 137,500 137,000 134,500 134,000
140 14 142,000 133,710 133,000 126,900 126,000
140 24 142,000 128,900 128,000 117,320 116,000
145 6 146,000 142,500 142,000 139,500 139,000
145 14 147,000 138,710 138,000 131,900 131,000
145 24 147,000 133,900 133,000 122,320 121,000
150 6 151,000 147,500 147,000 144,500 144,000
150 16 152,000 142,750 142,000 135,000 134,000
150 24 152,000 138,900 138,000 127,320 126,000

TTabablele 2 2 ((ccoonnttiinnueuedd))
Major
Nominal
Pitch diameter Minor diameter
diameter
diameter Pitch
D P D D D D D
4 min 2 max 2 min 1 max 1 min
155 6 156,000 152,500 152,000 149,500 149,000
155 16 157,
...

FINAL DRAFT
International
Standard
ISO/FDIS 2903-2
ISO/TC 1
ISO metric trapezoidal screw
Secretariat: SAC
threads — Tolerances —
Voting begins on:
2025-04-23
Part 2:
Limits of sizes
Voting terminates on:
2025-06-18
Filetages métriques trapézoïdaux ISO — Tolérances —
Partie 2: Limites de tailles
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number
ISO/FDIS 2903-2:2025(en) © ISO 2025

FINAL DRAFT
ISO/FDIS 2903-2:2025(en)
International
Standard
ISO/FDIS 2903-2
ISO/TC 1
ISO metric trapezoidal screw
Secretariat: SAC
threads — Tolerances —
Voting begins on:
Part 2:
Limits of sizes
Voting terminates on:
Filetages métriques trapézoïdaux ISO — Tolérances —
Partie 2: Limites de tailles
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
© ISO 2025
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
or ISO’s member body in the country of the requester.
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland Reference number
ISO/FDIS 2903-2:2025(en) © ISO 2025

ii
ISO/FDIS 2903-2:2025(en)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Limits of sizes . 1
4.1 General .1
4.2 Internal threads.2
4.3 External threads .14
Bibliography .31

iii
ISO/FDIS 2903-2:2025(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 1, Screw threads.
A list of all parts in the ISO 2903 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iv
FINAL DRAFT International Standard ISO/FDIS 2903-2:2025(en)
ISO metric trapezoidal screw threads — Tolerances —
Part 2:
Limits of sizes
1 Scope
This document specifies the limits of sizes for major, pitch and minor diameters of ISO metric trapezoidal
screw threads (Tr) conforming to ISO 2902 and having basic and design profiles in accordance with ISO 2901.
This document is applicable to the metric trapezoidal screw threads with the seven tolerance classes (7H,
8H, 9H, 7e, 8e, 8c and 9c) recommended in ISO 2903.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 2903, ISO metric trapezoidal screw threads — Tolerances
ISO 5408, Screw threads — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 5408 apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Limits of sizes
4.1 General
The limits of sizes specified shall be derived from the fundamental deviations and tolerances specified in
ISO 2903.
The limits of sizes for major, pitch and minor diameters of screw threads (Tr) have been calculated by the
following formulae and rounded to the third decimal place.

ISO/FDIS 2903-2:2025(en)
Internal thread
Major diameter D = D + 2a
4,min c
Pitch diameter D = D = D – 0,5P
2,min 2
D = D + T
2,max 2,min D2
Minor diameter D = D = D – P
1,min 1
D = D + T
1,max 1,min D1
External thread
Major diameter d = d
max
d = d – T
min d
Pitch diameter d = d + es = d – 0,5P + es
2,max 2
d = d – T
2,min 2,max d2
Minor diameter d = d – 2a = d – P – 2a
3,max 1 c c
d = d – T
3,min 3,max d3
Where es is a negative value.
For the symbols and their definitions see ISO 2903.
The maximum major diameter of internal thread D is not specified.
4,max
For the seven tolerance classes and nominal diameter ranges see Table 1.
Table 1 — Tr screw threads with the seven recommended tolerance classes
Nominal diameter
Screw thread Tolerance class Table number
mm
7H Table 2
From 8 to 300
Internal thread 8H Table 3
9H From 8 to 100 Table 4
7e Table 5
8e From 8 to 300 Table 6
External thread
8c Table 7
9c From 8 to 100 Table 8
4.2 Internal threads
Limits of sizes for the internal threads with tolerance class 7H shall be as specified in Table 2.

ISO/FDIS 2903-2:2025(en)
Table 2 — Limits of sizes for the internal threads with tolerance class 7H
Dimensions in millimetres
Major diam-
Nominal diam-
Pitch diameter Minor diameter
eter
eter Pitch
D P D D D D D
4,min 2,max 2,min 1,max 1,min
8 1,5 8,300 7,474 7,250 6,690 6,500
9 1,5 9,300 8,474 8,250 7,690 7,500
9 2 9,500 8,250 8,000 7,236 7,000
10 1,5 10,300 9,474 9,250 8,690 8,500
10 2 10,500 9,250 9,000 8,236 8,000
11 2 11,500 10,250 10,000 9,236 9,000
11 3 11,500 9,780 9,500 8,315 8,000
12 2 12,500 11,265 11,000 10,236 10,000
12 3 12,500 10,800 10,500 9,315 9,000
14 2 14,500 13,265 13,000 12,236 12,000
14 3 14,500 12,800 12,500 11,315 11,000
16 2 16,500 15,265 15,000 14,236 14,000
16 4 16,500 14,355 14,000 12,375 12,000
18 2 18,500 17,265 17,000 16,236 16,000
18 4 18,500 16,355 16,000 14,375 14,000
20 2 20,500 19,265 19,000 18,236 18,000
20 4 20,500 18,355 18,000 16,375 16,000
22 3 22,500 20,800 20,500 19,315 19,000
22 5 22,500 19,875 19,500 17,450 17,000
22 8 23,000 18,475 18,000 14,630 14,000
24 3 24,500 22,835 22,500 21,315 21,000
24 5 24,500 21,900 21,500 19,450 19,000
24 8 25,000 20,500 20,000 16,630 16,000
26 3 26,500 24,835 24,500 23,315 23,000
26 5 26,500 23,900 23,500 21,450 21,000
26 8 27,000 22,500 22,000 18,630 18,000
28 3 28,500 26,835 26,500 25,315 25,000
28 5 28,500 25,900 25,500 23,450 23,000
28 8 29,000 24,500 24,000 20,630 20,000
30 3 30,500 28,835 28,500 27,315 27,000
30 6 31,000 27,450 27,000 24,500 24,000
30 10 31,000 25,530 25,000 20,710 20,000
32 3 32,500 30,835 30,500 29,315 29,000
32 6 33,000 29,450 29,000 26,500 26,000
32 10 33,000 27,530 27,000 22,710 22,000
34 3 34,500 32,835 32,500 31,315 31,000
34 6 35,000 31,450 31,000 28,500 28,000
34 10 35,000 29,530 29,000 24,710 24,000
36 3 36,500 34,835 34,500 33,315 33,000
36 6 37,000 33,450 33,000 30,500 30,000
36 10 37,000 31,530 31,000 26,710 26,000

ISO/FDIS 2903-2:2025(en)
TTabablele 2 2 ((ccoonnttiinnueuedd))
Major diam-
Nominal diam-
Pitch diameter Minor diameter
eter
eter Pitch
D P D D D D D
4,min 2,max 2,min 1,max 1,min
38 3 38,500 36,835 36,500 35,315 35,000
38 7 39,000 34,975 34,500 31,560 31,000
38 10 39,000 33,530 33,000 28,710 28,000
40 3 40,500 38,835 38,500 37,315 37,000
40 7 41,000 36,975 36,500 33,560 33,000
40 10 41,000 35,530 35,000 30,710 30,000
42 3 42,500 40,835 40,500 39,315 39,000
42 7 43,000 38,975 38,500 35,560 35,000
42 10 43,000 37,530 37,000 32,710 32,000
44 3 44,500 42,835 42,500 41,315 41,000
44 7 45,000 40,975 40,500 37,560 37,000
44 12 45,000 38,560 38,000 32,800 32,000
46 3 46,500 44,855 44,500 43,315 43,000
46 8 47,000 42,530 42,000 38,630 38,000
46 12 47,000 40,630 40,000 34,800 34,000
48 3 48,500 46,855 46,500 45,315 45,000
48 8 49,000 44,530 44,000 40,630 40,000
48 12 49,000 42,630 42,000 36,800 36,000
50 3 50,500 48,855 48,500 47,315 47,000
50 8 51,000 46,530 46,000 42,630 42,000
50 12 51,000 44,630 44,000 38,800 38,000
52 3 52,500 50,855 50,500 49,315 49,000
52 8 53,000 48,530 48,000 44,630 44,000
52 12 53,000 46,630 46,000 40,800 40,000
55 3 55,500 53,855 53,500 52,315 52,000
55 9 56,000 51,060 50,500 46,670 46,000
55 14 57,000 48,670 48,000 41,900 41,000
60 3 60,500 58,855 58,500 57,315 57,000
60 9 61,000 56,060 55,500 51,670 51,000
60 14 62,000 53,670 53,000 46,900 46,000
65 4 65,500 63,400 63,000 61,375 61,000
65 10 66,000 60,560 60,000 55,710 55,000
65 16 67,000 57,710 57,000 50,000 49,000
70 4 70,500 68,400 68,000 66,375 66,000
70 10 71,000 65,560 65,000 60,710 60,000
70 16 72,000 62,710 62,000 55,000 54,000
75 4 75,500 73,400 73,000 71,375 71,000
75 10 76,000 70,560 70,000 65,710 65,000
75 16 77,000 67,710 67,000 60,000 59,000
80 4 80,500 78,400 78,000 76,375 76,000
80 10 81,000 75,560 75,000 70,710 70,000
80 16 82,000 72,710 72,000 65,000 64,000

ISO/FDIS 2903-2:2025(en)
TTabablele 2 2 ((ccoonnttiinnueuedd))
Major diam-
Nominal diam-
Pitch diameter Minor diameter
eter
eter Pitch
D P D D D D D
4,min 2,max 2,min 1,max 1,min
85 4 85,500 83,400 83,000 81,375 81,000
85 12 86,000 79,630 79,000 73,800 73,000
85 18 87,000 76,750 76,000 68,120 67,000
90 4 90,500 88,400 88,000 86,375 86,000
90 12 91,000 84,630 84,000 78,800 78,000
90 18 92,000 81,750 81,000 73,120 72,000
95 4 95,500 93,425 93,000 91,375 91,000
95 12 96,000 89,670 89,000 83,800 83,000
95 18 97,000 86,800 86,000 78,120 77,000
100 4 100,500 98,425 98,000 96,375 96,000
100 12 101,000 94,670 94,000 88,800 88,000
100 20 102,000 90,800 90,000 81,180 80,000
105 4 105,500 103,425 103,000 101,375 101,000
105 12 106,000 99,670 99,000 93,800 93,000
105 20 107,000 95,800 95,000 86,180 85,000
110 4 110,500 108,425 108,000 106,375 106,000
110 12 111,000 104,670 104,000 98,800 98,000
110 20 112,000 100,800 100,000 91,180 90,00
...

ISO/FDIS 2903-2:2025(en)
ISO/TC 1
Secretariat: SAC
Date: 2025-03-0504-08
ISO metric trapezoidal screw threads — Tolerances —
—
Part 2:
Limits of sizes
Filetages métriques trapézoïdaux ISO — Tolérances —
—
Partie 2: Dimensions limitesLimites de tailles
FDIS stage
ISO #####-#:####(X/FDIS 2903-2:2025(en)
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication
may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying,
or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO
at the address below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: + 41 22 749 01 11
EmailE-mail: [e-mail]
Website: www.iso.org
Published in Switzerland
© ISO #### 2025 – All rights reserved
ii
ISO/FDIS 2903-2:2025(en)
Contents
Foreword . Error! Bookmark not defined.
1 Scope . Error! Bookmark not defined.
2 Normative references . Error! Bookmark not defined.
3 Terms and definitions . Error! Bookmark not defined.
4 Limits of sizes . Error! Bookmark not defined.
4.1 General . Error! Bookmark not defined.
4.2 Internal threads . Error! Bookmark not defined.
4.3 External threads . Error! Bookmark not defined.
Bibliography . Error! Bookmark not defined.

iii
ISO #####-#:####(X/FDIS 2903-2:2025(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types of
ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights
in respect thereof. As of the date of publication of this document, ISO had not received notice of (a) patent(s)
which may be required to implement this document. However, implementers are cautioned that this may not
represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 1, Screw threads.
A list of all parts in the ISO 2903 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
© ISO #### 2025 – All rights reserved
iv
FINAL DRAFT International Standard ISO/FDIS 2903-2:2025(en)

ISO metric trapezoidal screw threads — Tolerances —
—
Part 2:
Limits of sizes
1 Scope
This document specifies the limits of sizes for major, pitch and minor diameters of ISO metric trapezoidal
screw threads (Tr) conforming to ISO 2902 and having basic and design profiles in accordance with ISO 2901.
This document is applicable to the metric trapezoidal screw threads with the seven tolerance classes (7H, 8H,
9H, 7e, 8e, 8c and 9c) recommended in ISO 2903.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 2903, ISO metric trapezoidal screw threads — Tolerances
ISO 5408, Screw threads — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 5408 apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— — ISO Online browsing platform: available at https://www.iso.org/obp
— — IEC Electropedia: available at https://www.electropedia.org/
4 Limits of sizes
4.1 General
The limits of sizes specified shall be derived from the fundamental deviations and tolerances specified in ISO
2903.
The limits of sizes for major, pitch and minor diameters of screw threads (Tr) have been calculated by the
following formulae and rounded to the third decimal place.
Internal thread
Major diameter D = D + 2a
4,min c
Pitch diameter D = D = D – 0,5P
2,min 2
ISO #####-#:####(X/FDIS 2903-2:2025(en)
D = D + T
2,max 2,min D2
Minor diameter D = D = D – P
1,min 1
D = D + T
1,max 1,min D1
External thread
Major diameter d d = d
max max
d d = d – T
min min d
Pitch diameter d = d + es = d – 0,5P + es
2,max 2
d = d – T
2,min 2,max d2
Minor diameter d = d – 2a = d – P – 2a
3,max 1 c c
d = d – T
3,min 3,max d3
Where es is a negative value.
For the symbols and their definitions see ISO 2903.
The maximum major diameter of internal thread D is not specified.
4,max
For the seven tolerance classes and nominal diameter ranges see Table 1Table 1.
Table 1 — Tr screw threads with the seven recommended tolerance classes
Nominal diameter
Screw thread Tolerance class Table number
mm
7H Table 2Table 2
From 8 to 300
Internal thread 8H Table 3Table 3
9H From 8 to 100 Table 4Table 4
7e Table 5Table 5
8e From 8 to 300 Table 6Table 6
External thread
8c Table 7Table 7
9c From 8 to 100 Table 8Table 8
4.2 Internal threads
Limits of sizes for the internal threads with tolerance class 7H shall be as specified in Table 2Table 2.
Table 2 — Limits of sizes for the internal threads with tolerance class 7H
Dimensions in millimetres
Major
Nominal
Pitch diameter Minor diameter
diameter
diameter Pitch
D P D D D D D
4,min 2,max 2,min 1,max 1,min
8 1,5 8,300 7,474 7,250 6,690 6,500
9 1,5 9,300 8,474 8,250 7,690 7,500
9 2 9,500 8,250 8,000 7,236 7,000
10 1,5 10,300 9,474 9,250 8,690 8,500
© ISO #### 2025 – All rights reserved
ISO/FDIS 2903-2:2025(en)
Major
Nominal
Pitch diameter Minor diameter
diameter
diameter Pitch
D P D D D D D
4,min 2,max 2,min 1,max 1,min
10 2 10,500 9,250 9,000 8,236 8,000
11 2 11,500 10,250 10,000 9,236 9,000
11 3 11,500 9,780 9,500 8,315 8,000
12 2 12,500 11,265 11,000 10,236 10,000
12 3 12,500 10,800 10,500 9,315 9,000
14 2 14,500 13,265 13,000 12,236 12,000
14 3 14,500 12,800 12,500 11,315 11,000
16 2 16,500 15,265 15,000 14,236 14,000
16 4 16,500 14,355 14,000 12,375 12,000
18 2 18,500 17,265 17,000 16,236 16,000
18 4 18,500 16,355 16,000 14,375 14,000
20 2 20,500 19,265 19,000 18,236 18,000
20 4 20,500 18,355 18,000 16,375 16,000
22 3 22,500 20,800 20,500 19,315 19,000
22 5 22,500 19,875 19,500 17,450 17,000
22 8 23,000 18,475 18,000 14,630 14,000
24 3 24,500 22,835 22,500 21,315 21,000
24 5 24,500 21,900 21,500 19,450 19,000
24 8 25,000 20,500 20,000 16,630 16,000
26 3 26,500 24,835 24,500 23,315 23,000
26 5 26,500 23,900 23,500 21,450 21,000
26 8 27,000 22,500 22,000 18,630 18,000
28 3 28,500 26,835 26,500 25,315 25,000
28 5 28,500 25,900 25,500 23,450 23,000
28 8 29,000 24,500 24,000 20,630 20,000
30 3 30,500 28,835 28,500 27,315 27,000
30 6 31,000 27,450 27,000 24,500 24,000
30 10 31,000 25,530 25,000 20,710 20,000
32 3 32,500 30,835 30,500 29,315 29,000
32 6 33,000 29,450 29,000 26,500 26,000
32 10 33,000 27,530 27,000 22,710 22,000
34 3 34,500 32,835 32,500 31,315 31,000
34 6 35,000 31,450 31,000 28,500 28,000
34 10 35,000 29,530 29,000 24,710 24,000
36 3 36,500 34,835 34,500 33,315 33,000
ISO #####-#:####(X/FDIS 2903-2:2025(en)
Major
Nominal
Pitch diameter Minor diameter
diameter
diameter Pitch
D P D D D D D
4,min 2,max 2,min 1,max 1,min
36 6 37,000 33,450 33,000 30,500 30,000
36 10 37,000 31,530 31,000 26,710 26,000
38 3 38,500 36,835 36,500 35,315 35,000
38 7 39,000 34,975 34,500 31,560 31,000
38 10 39,000 33,530 33,000 28,710 28,000
40 3 40,500 38,835 38,500 37,315 37,000
40 7 41,000 36,975 36,500 33,560 33,000
40 10 41,000 35,530 35,000 30,710 30,000
42 3 42,500 40,835 40,500 39,315 39,000
42 7 43,000 38,975 38,500 35,560 35,000
42 10 43,000 37,530 37,000 32,710 32,000
44 3 44,500 42,835 42,500 41,315 41,000
44 7 45,000 40,975 40,500 37,560 37,000
44 12 45,000 38,560 38,000 32,800 32,000
46 3 46,500 44,855 44,500 43,315 43,000
46 8 47,000 42,530 42,000 38,630 38,000
46 12 47,000 40,630 40,000 34,800 34,000
48 3 48,500 46,855 46,500 45,315 45,000
48 8 49,000 44,530 44,000 40,630 40,000
48 12 49,000 42,630 42,000 36,800 36,000
50 3 50,500 48,855 48,500 47,315 47,000
50 8 51,000 46,530 46,000 42,630 42,000
50 12 51,000 44,630 44,000 38,800 38,000
52 3 52,500 50,855 50,500 49,315 49,000
52 8 53,000 48,530 48,000 44,630 44,000
52 12 53,000 46,630 46,000 40,800 40,000
55 3 55,500 53,855 53,500 52,315 52,000
55 9 56,000 51,060 50,500 46,670 46,000
55 14 57,000 48,670 48,000 41,900 41,000
60 3 60,500 58,855 58,500 57,315 57,000
60 9 61,000 56,060 55,500 51,670 51,000
60 14 62,000 53,670 53,000 46,900 46,000
65 4 65,500 63,400 63,000 61,375 61,000
65 10 66,000 60,560 60,000 55,710 55,000
65 16 67,000 57,710 57,000 50,000 49,000
© ISO #### 2025 – All rights reserved
ISO/FDIS 2903-2:2025(en)
Major
Nominal
Pitch diameter Minor diameter
diameter
diameter Pitch
D P D D D D D
4,min 2,max 2,min 1,max 1,min
70 4 70,500 68,400 68,000 66,375 66,000
70 10 71,000 65,560 65,000 60,710 60,000
70 16 72,000 62,710 62,000 55,000 54,000
75 4 75,500 73,400 73,000 71,375 71,000
75 10 76,000 70,560 70,000 65,710 65,000
75 16 77,000 67,710 67,000 60,000 59,000
80 4 80,500 78,400 78,000 76,375 76,000
80 10 81,000 75,560 75,000 70,710 70,000
80 16 82,000 72,710 72,000 65,000 64,000
85 4 85,500 83,400 83,000 81,375 81,000
85 12 86,000 79,630 79,000 73,800 73,000
85 18 87,000 76,750 76,000 68,120 67,000
90 4 90,500 88,400 88,000 86,375 86,000
90 12 91,000 84,630 84,000 78,800 78,000
90 18 92,000 81,750 81,000 73,120 72,000
95 4 95,500 93,425 93,000 91,375 91,000
95 12 96,000 89,670 89,000 83,800 83,000
95 18 97,000 86,800 86,000 78,120 77,000
100 4 100,500 98,425 98,000 96,375 96,000
100 12 101,000 94,670 94,000 88,800 88,000
100 20 102,000 90,800 90,000 81,180 80,000
105 4 105,500 103,425 103,000 101,375 101,000
105 12 106,000 99,670 99,000 93,800 93,000
105 20 107,000 95,800 95,000 86,180 85,000
110 4 110,500 108,425 108,000 106,375 106,000
110 12 111,000 104,670 104,000 98,800 98,000
110 20 112,000 100,800 100,000 91,180 90,000
115 6 116,000 112,500 112,000 109,500 109,000
115 14 117,000 108,710 108,000 101,900 101,000
115 22 117,000 104,850 104,000 94,250 93,000
120 6 121,000 117,500 117,000 114,500 114,000
120 14 122,000 113,710 113,000 106,900 106,000
120 22 122,000 109,850 109,000 99,250 98,000
125 6 126,000 122,500 122,000 119,500 119,000
125 14 127,000 118,710 118,000 111,900 111,000
ISO #####-#:####(X/FDIS 2903-2:2025(en)
Major
Nominal
Pitch diameter Minor diameter
diameter
diameter Pitch
D P D D D D D
4,min 2,max 2,min 1,max 1,min
125 22 127,000 114,850 114,000 104,250 103,000
130 6 131,000 127,500 127,000 124,500 124,000
130 14 132,000 123,710 123,000 116,900 116,000
130 22 132,000 119,850 119,000 109,250 108,000
135 6 136,000 132,500 132,000 129,500 129,000
135 14 137,000 128,710 128,000 121,900 121,000
135 24 137,000 123,900 123,000 112,320 111,000
140 6 141,000 137,500 137,000 134,500 134,000
140 14 142,000 133,710 133,000 126,900 126,000
140 24 142,000 128,900 128,000 117,320 116,000
145 6 146,000 142,500 142,000 139,500 139,000
145 14 147,000 138,710 138,000 131,900 131,000
145 24 147,000 133,900 133,000 122,320 121,000
150 6 151,000 147,500 147,000 144,500 144,000
150 16 152,000 142,750 142,000 135,000 134,000
150 24 152,000 138,900 138,000 127,320 126,000
155 6 156,000 152,500 152,000 149,500 149,000
155 16 157,000 147,750 147,000 140,000 139,000
155 24 157,000 143,900 143,000 132,320 131,000
160 6 161,000 157,500 157,000 154,500 154,000
160 16 162,000 152,750 152,000 145,000 144,000
160 28 162,000 146,950 146,000 133,500 132,000
165 6 166,000 162,500 162,000 159,500 159,000
165 16 167,000 157,750 157,000 150,000 149,000
165 28 167,000 151,950 151,000 138,500 1
...