ISO 724

ISO general purpose metric screw threads — Basic dimensions

Specifies the basic dimensions of metric threads in accordance with ISO 261. The basic dimensions are: basic major diameter of internal or external thread (nominal diameter), basic pitch diameter of internal or external thread, basic minor diameter of internal or external thread, height of fundamental triangle, pitch. The values refer to the basic profile in accordance with ISO 68.

Filetages métriques ISO pour usages généraux — Dimensions de base

General Information

• Status: Not Published
• ICS: 21.040.10 - Metric screw threads
• Technical Committee: ISO/TC 1 - Screw threads
• Drafting Committee: ISO/TC 1 - Screw threads
• Current Stage: 6000 - International Standard under publication
• Completion Date: 22-Mar-2023

Relations

• Revises: ISO 724:1993 - ISO general-purpose metric screw threads — Basic dimensions
• Effective Date: 06-Jun-2022

Standards Content (Sample)

ISO /PRF 724:2023(E)
ISO /TC 1
Date: 2022-12-29
Secretariat: SAC
Date: 2023-02-22
ISO general purpose metric screw threads — Basic dimensions
Filetages métriques ISO pour usages généraux — Dimensions de base
FDIS stage
---------------------- Page: 1 ----------------------
ISO /PRF 724:2023(E)
© ISO 2023

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.orgwww.iso.org
Published in Switzerland
ii © ISO 2023 – All rights reserved
ii © ISO 2023 – All rights reserved
---------------------- Page: 2 ----------------------
ISO /PRF 724:2023(E)
Contents

Foreword ............................................................................................................................................................................................ iv

1 Scope ....................................................................................................................................................................................... 1

2 Normative references ....................................................................................................................................................... 1

3 Terms and definitions ...................................................................................................................................................... 1

4 Symbols .................................................................................................................................................................................. 1

5 Basic dimensions ................................................................................................................................................................ 1

Bibliography .................................................................................................................................................................................... 13

© ISO 2023 – All rights reserved iii
© ISO 2023 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO /PRF 724:2023(E)
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 documents 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).
Field Code Changed

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any

patent rights identified during the development of the document will be in the Introduction and/or on

the ISO list of patent declarations received (see www.iso.org/patentswww.iso.org/patents).

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.htmlwww.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 1, Screw threads.

This third edition cancels and replaces the second edition (ISO 724:1993, including Cor 1:2009), which

has been technically revised.
The main changes are as follows:
— — “basic profile” has been replaced with “design profile” in the Scope;
— — a second paragraph has been added in the Scope;
— — three symbols, d , H and h , have been added in Clause 4;Clause 4;
3 1 3

— — the values and formula for the minor diameter of external thread, d , have been added in

Table 1Table 1 and Clause 5;Clause 5;
— — ISO 68-1 and ISO 261 have been added in the Bibliography.

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.
Field Code Changed
iv © ISO 2023 – All rights reserved
iv © ISO 2023 – All rights reserved
---------------------- Page: 4 ----------------------
INTERNATIONAL STANDARD ISO 724:2023(E)
ISO general purpose metric screw threads — Basic dimensions
1 Scope

This document specifies the basic dimensions of ISO general purpose metric screw threads according to

ISO 261. The values refer to the design profiles according to ISO 68-1.
This document is applicable to the metric fastening screw threads.
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 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/obphttps://www.iso.org/obp

— — IEC Electropedia: available at https://www.electropedia.org/https://www.electropedia.org/

4 Symbols
For the purposes of this document, the following symbols apply.
D major diameter of internal thread (nominal diameter)
d major diameter of external thread (nominal diameter)
D pitch diameter of internal thread
d pitch diameter of external thread
D minor diameter of internal thread
d minor diameter of external thread on design profile
P pitch
H fundamental triangle height
H1 thread height of internal thread on design profile
h thread height of external thread on design profile
5 Basic dimensions
Basic dimensions shown in Figure 1Figure 1 are given in Table 1.Table 1.

The values of D , d , D , and d , in Table 1,Table 1, have been calculated from the following formulae and

2 2 1 3
rounded to the third decimal place.
D = d = d – 2 × 3H/8 = d – 0,649 519 P
2 2
D = d – 2 × H = d – 1,082 532 P
1 1
d = d – 2 × h = d – 1,226 869 P
3 3
© ISO 2023 – All rights reserved 1
---------------------- Page: 5 ----------------------
ISO /PRF 724:2023(E)
Key
1 internal thread
2 external thread
Figure 1 — Basic dimensions on design profiles
Table 1 — Basic dimensions
Dimensions in millimetres
Minor diameter
Nominal diameter,
Pitch Pitch diameter
Internal thread External thread
major diameter
flat crest rounded root
D, d P D2, d2 D1 d3
0,2 0,870 0,783 0,755
0,25 0,838 0,729 0,693
0,2 0,970 0,883 0,855
1,1
0,25 0,938 0,829 0,793
0,2 1,070 0,983 0,955
1,2
0,25 1,038 0,929 0,893
1,4 0,2 1,270 1,183 1,155
2 © ISO 2023 – All rights reserved
2 © ISO 2023 – All rights reserved
---------------------- Page: 6 ----------------------
ISO /PRF 724:2023(E)
Minor diameter
Nominal diameter,
Pitch Pitch diameter
Internal thread External thread
major diameter
flat crest rounded root
D, d P D2, d2 D1 d3
0,3 1,205 1,075 1,032
0,2 1,470 1,383 1,355
1,6
0,35 1,373 1,221 1,171
0,2 1,670 1,583 1,555
1,8
0,35 1,573 1,421 1,371
0,25 1,838 1,729 1,693
0,4 1,740 1,567 1,509
0,25 2,038 1,929 1,893
2,2
0,45 1,908 1,713 1,648
0,35 2,273 2,121 2,071
2,5
0,45 2,208 2,013 1,948
0,35 2,773 2,621 2,571
0,5 2,675 2,459 2,387
0,35 3,273 3,121 3,071
3,5
0,6 3,110 2,850 2,764
0,5 3,675 3,459 3,387
0,7 3,545 3,242 3,141
0,5 4,175 3,959 3,887
4,5
0,75 4,013 3,688 3,580
0,5 4,675 4,459 4,387
0,8 4,480 4,134 4,019
5,5 0,5 5,175 4,959 4,887
0,75 5,513 5,188 5,080
1 5,350 4,917 4,773
0,75 6,513 6,188 6,080
1 6,350 5,917 5,773
0,75 7,513 7,188 7,080
8 1 7,350 6,917 6,773
1,25 7,188 6,647 6,466
0,75 8,513 8,188 8,080
9 1 8,350 7,917 7,773
1,25 8,188 7,647 7,466
0,75 9,513 9,188 9,080
1 9,350 8,917 8,773
1,25 9,188 8,647 8,466
1,5 9,026 8,376 8,160
© ISO 2023 – All rights reserved 3
© ISO 2023 – All rights reserved 3
---------------------- Page: 7 ----------------------
ISO /PRF 724:2023(E)
Minor diameter
Nominal diameter,
Pitch Pitch diameter
Internal thread External thread
major diameter
flat crest rounded root
D, d P D2, d2 D1 d3
0,75 10,513 10,188 10,080
11 1 10,350 9,917 9,773
1,5 10,026 9,376 9,160
1 11,350 10,917 10,773
1,25 11,188 10,647 10,466
1,5 11,026 10,376 10,160
1,75 10,863 10,106 9,853
1 13,350 12,917 12,773
14 1,5 13,026 12,376 12,160
2 12,701 11,835 11,546
1 14,350 13,917 13,773
1,5 14,026 13,376 13,160
1 15,350 14,917 14,773
16 1,5 15,026 14,376 14,160
2 14,701 13,835 13,546
1 16,350 15,917 15,773
1,5 16,026 15,376 15,160
1 17,350 16,917 16,773
1,5 17,026 16,376 16,160
2 16,701 15,835 15,546
2,5 16,376 15,294 14,933
1 19,350 18,917 18,773
1,5 19,026 18,376 18,160
2 18,701 17,835 17,546
2,5 18,376 17,294 16,933
1 21,350 20,917 20,773
1,5 21,026 20,376 20,160
2 20,701 19,835 19,546
2,5 20,376 19,294 18,93
...

INTERNATIONAL ISO
STANDARD 724
Third edition
ISO general purpose metric screw
threads — Basic dimensions
Filetages métriques ISO pour usages généraux — Dimensions de base
PROOF/ÉPREUVE
Reference number
ISO 724:2023(E)
© ISO 2023
---------------------- Page: 1 ----------------------
ISO 724:2023(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2023

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
PROOF/ÉPREUVE © ISO 2023 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 724:2023(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ..................................................................................................................................................................................... 1

3 Terms and definitions .................................................................................................................................................................................... 1

4 Symbols .......................................................................................................................................................................................................................... 1

5 Basic dimensions ................................................................................................................................................................................................. 2

Bibliography .............................................................................................................................................................................................................................12

iii
© ISO 2023 – All rights reserved PROOF/ÉPREUVE
---------------------- Page: 3 ----------------------
ISO 724:2023(E)
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 documents 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).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www.iso.org/patents).

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.

This third edition cancels and replaces the second edition (ISO 724:1993, including Cor 1:2009), which

has been technically revised.
The main changes are as follows:
— “basic profile” has been replaced with “design profile” in the Scope;
— a second paragraph has been added in the Scope;
— three symbols, d , H and h , have been added in Clause 4;
3 1 3

— the values and formula for the minor diameter of external thread, d , have been added in Table 1 and

Clause 5;
— ISO 68-1 and ISO 261 have been added in the Bibliography.

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.
PROOF/ÉPREUVE © ISO 2023 – All rights reserved
---------------------- Page: 4 ----------------------
INTERNATIONAL STANDARD ISO 724:2023(E)
ISO general purpose metric screw threads — Basic
dimensions
1 Scope

This document specifies the basic dimensions of ISO general purpose metric screw threads according

to ISO 261. The values refer to the design profiles according to ISO 68-1.
This document is applicable to the metric fastening screw threads.
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 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 Symbols
For the purposes of this document, the following symbols apply.
D major diameter of internal thread (nominal diameter)
d major diameter of external thread (nominal diameter)
D pitch diameter of internal thread
d pitch diameter of external thread
D minor diameter of internal thread
d minor diameter of external thread on design profile
P pitch
H fundamental triangle height
H thread height of internal thread on design profile
h thread height of external thread on design profile
© ISO 2023 – All rights reserved PROOF/ÉPREUVE
---------------------- Page: 5 ----------------------
ISO 724:2023(E)
5 Basic dimensions
Basic dimensions shown in Figure 1 are given in Table 1.

The values of D , d , D and d , in Table 1, have been calculated from the following formulae and rounded

2 2 1 3
to the third decimal place.
D = d = d – 2 × 3H/8 = d – 0,649 519 P
2 2
D = d – 2 × H = d – 1,082 532 P
1 1
d = d – 2 × h = d – 1,226 869 P
3 3
Key
1 internal thread
2 external thread
Figure 1 — Basic dimensions on design profiles
Table 1 — Basic dimensions
Dimensions in millimetres
Minor diameter
Nominal diameter,
Internal thread External thread
Pitch Pitch diameter
major diameter
flat crest rounded root
D, d P D , d D d
2 2 1 3
0,2 0,870 0,783 0,755
0,25 0,838 0,729 0,693
0,2 0,970 0,883 0,855
1,1
0,25 0,938 0,829 0,793
0,2 1,070 0,983 0,955
1,2
0,25 1,038 0,929 0,893
0,2 1,270 1,183 1,155
1,4
0,3 1,205 1,075 1,032
PROOF/ÉPREUVE © ISO 2023 – All rights reserved
---------------------- Page: 6 ----------------------
ISO 724:2023(E)
TTabablele 1 1 ((ccoonnttiinnueuedd))
Minor diameter
Nominal diameter,
Internal thread External thread
Pitch Pitch diameter
major diameter
flat crest rounded root
D, d P D , d D d
2 2 1 3
0,2 1,470 1,383 1,355
1,6
0,35 1,373 1,221 1,171
0,2 1,670 1,583 1,555
1,8
0,35 1,573 1,421 1,371
0,25 1,838 1,729 1,693
0,4 1,740 1,567 1,509
0,25 2,038 1,929 1,893
2,2
0,45 1,908 1,713 1,648
0,35 2,273 2,121 2,071
2,5
0,45 2,208 2,013 1,948
0,35 2,773 2,621 2,571
0,5 2,675 2,459 2,387
0,35 3,273 3,121 3,071
3,5
0,6 3,110 2,850 2,764
0,5 3,675 3,459 3,387
0,7 3,545 3,242 3,141
0,5 4,175 3,959 3,887
4,5
0,75 4,013 3,688 3,580
0,5 4,675 4,459 4,387
0,8 4,480 4,134 4,019
5,5 0,5 5,175 4,959 4,887
0,75 5,513 5,188 5,080
1 5,350 4,917 4,773
0,75 6,513 6,188 6,080
1 6,350 5,917 5,773
0,75 7,513 7,188 7,080
8 1 7,350 6,917 6,773
1,25 7,188 6,647 6,466
0,75 8,513 8,188 8,080
9 1 8,350 7,917 7,773
1,25 8,188 7,647 7,466
0,75 9,513 9,188 9,080
1 9,350 8,917 8,773
1,25 9,188 8,647 8,466
1,5 9,026 8,376 8,160
0,75 10,513 10,188 10,080
11 1 10,350 9,917 9,773
1,5 10,026 9,376 9,160
© ISO 2023 – All rights reserved PROOF/ÉPREUVE
---------------------- Page: 7 ----------------------
ISO 724:2023(E)
TTabablele 1 1 ((ccoonnttiinnueuedd))
Minor diameter
Nominal diameter,
Internal thread External thread
Pitch Pitch diameter
major diameter
flat crest rounded root
D, d P D , d D d
2 2 1 3
1 11,350 10,917 10,773
1,25 11,188 10,647 10,466
1,5 11,026 10,376 10,160
1,75 10,863 10,106 9,853
1 13,350 12,917 12,773
14 1,5 13,026 12,376 12,160
2 12,701 11,835 11,546
1 14,350 13,917 13,773
1,5 14,026 13,376 13,160
1 15,350 14,917 14,773
16 1,5 15,026 14,376 14,160
2 14,701 13,835 13,546
1 16,350 15,917 15,773
1,5 16,026 15,376 15,160
1 17,350 16,917 16,773
1,5 17,026 16,376 16,160
2 16,701 15,835 15,546
2,5 16,376 15,294 14,933
1 19,350 18,917 18,773
1,5 19,026 18,376 1
...