kSIST-TS FprCEN/TS 18405:2026

• Abstract:

  This document provides guidance to harmonize the expression of metrological information such as measurement uncertainties and decision rules in standards for furniture.; This document clarifies how to deal with measurement uncertainty of measurement results, and how to express information concerning measurement uncertainty in furniture standards.

• Status: Not Published
• Public Enquiry End Date: 01-Nov-2026
• ICS: 17.020 - Metrology and measurement in general
• ICS: 97.140 - Furniture
• Technical Committee: POH - Furniture
• Current Stage: 5520 - Unique Acceptance Procedure (UAP) (Adopted Project)
• Start Date: 09-Sep-2026
• Due Date: 27-Jan-2027
• Ref Project: FprCEN/TS 18405 - Furniture - General guidelines about measurement uncertainty

kSIST-TS FprCEN/TS 18405:2026 is the Slovenian standard published by SIST, identical to FprCEN/TS 18405. It gives general guidance on measurement uncertainty for furniture standards and explains how to express uncertainty, decision rules and tolerances for furniture measurements and tests. It is aimed at people who write, run or assess furniture test methods and conformity statements.

What does kSIST-TS FprCEN/TS 18405:2026 specify?

kSIST-TS FprCEN/TS 18405:2026 specifies guidance for harmonizing metrological information in furniture standards. It helps standards writers and laboratories describe measurement uncertainty, decide conformity, and handle tolerances in a consistent way.

The document is organized into six clauses and two informative annexes.

Part	What it covers
Clause 1	Scope
Clause 2	Normative references
Clause 3	Terms and definitions
Clause 4	Measurement uncertainty
Clause 5	Decision rule
Clause 6	Tolerances
Annex A	Example of measurement uncertainty evaluation
Annex B	Interlaboratory comparisons (collaborative trials)

Annex A is split into continuous-scale, discrete-scale and pass/fail results. Annex B focuses on collaborative trials and how they relate to uncertainty and repeatability/reproducibility.

What are the key requirements of kSIST-TS FprCEN/TS 18405:2026?

Measurement uncertainty

Clause 4.1 says measurement uncertainty shall be considered whenever a standard refers to a quantity to be measured. It points to common contributors such as sampling, method, equipment, environment, operator, time and place, so the test method has to make those influences visible instead of treating the result as exact.

Clause 4.2 distinguishes repeatability and reproducibility. Repeatability means the same procedure, operator, measuring system, operating conditions and location over a short time, while reproducibility allows different locations, operators and systems. In practice, this tells a lab whether it is looking at within-lab variation or between-lab spread.

Clause 4.3 recommends that a standard state the target measurement uncertainty, any interlaboratory comparison results, the reference documents used for the calculation, and any neglected contributions. That gives labs a clear uncertainty target and a record of what was and was not counted.

Decision rules

Clause 5.1 says a standard with acceptability limits or ranges should state how compliance is checked for a measurement result with uncertainty. This avoids different laboratories making different conformity decisions from the same result.

Clause 5.2 gives one decision rule: compare the measured value directly with the requirement and ignore the uncertainty. Clause 5.3 gives another: compare the measured value with the requirement after allowing for the expanded measurement uncertainty U. In practice, the second approach is stricter near the limit and requires the uncertainty to be known.

Clause 5.4 allows different requirements in the same standard to use different decision rules. It also links the choice of rule to the risk of false acceptance and false rejection, which matters when a conformity statement is issued.

Tolerances

Clause 6 says that when test methods use tolerances for quantities such as mass, force or time, the standard shall state a decision rule for compliance evaluation. For users, this means the tolerance alone is not enough - the rule for combining the result and its uncertainty has to be defined too.

What terms does kSIST-TS FprCEN/TS 18405:2026 define?

• Quantity - a property that can be expressed by a number and a reference.
• Measurement uncertainty - a non-negative parameter that describes the dispersion of values attributed to a measurand.
• Measurement result - the set of values attributed to a measurand together with relevant information, usually a measured value plus uncertainty.
• Expanded measurement uncertainty U - the combined standard uncertainty multiplied by a factor larger than 1.
• Target measurement uncertainty - an upper limit for uncertainty set for the intended use of the results.
• Repeatability condition of measurement - measurement under the same procedure, operator, system, conditions and location over a short period.
• Reproducibility condition of measurement - measurement under changing locations, operators or systems over a short period.
• Decision rule - the rule used to decide whether a measurement result meets a requirement.

Who uses kSIST-TS FprCEN/TS 18405:2026?

kSIST-TS FprCEN/TS 18405:2026 is used by furniture standards writers, testing and calibration laboratories, manufacturers, quality managers and conformity assessment teams. It is especially relevant where furniture standards set dimensional, strength, durability or surface-performance requirements and the result is a measured value with uncertainty. It also supports laboratories that need to document a conformity decision under EN ISO/IEC 17025:2017.

Which standards are used with kSIST-TS FprCEN/TS 18405:2026?

• EN ISO/IEC 17025:2017 - competence requirements for testing and calibration laboratories; it is the main normative reference for documenting decision rules in conformity statements.
• JCGM 200:2012 - provides the metrology vocabulary used for terms such as quantity, measurement uncertainty and measurement result.
• ISO 5725-1:2023 - provides the accuracy and precision definitions used for repeatability and reproducibility limits.
• JCGM 100:2008 - gives the general approach to evaluating and expressing measurement uncertainty.
• JCGM 106:2012 - gives further guidance on measurement uncertainty in conformity assessment and on consumer and producer risk.
• EN ISO/IEC 17043 and ISO 13528 - support interlaboratory comparisons and proficiency testing design in Annex B.
• EN 1335-1:2020+A1:2022, ISO 24496, EN 1730:2012, EN 12720, EN 12722 and CEN/TR 17292 - are cited as furniture-related examples where uncertainty, repeatability or reproducibility are applied.

What does the kSIST-TS FprCEN/TS 18405:2026 document contain?

The document contains a short core text plus two informative annexes. Clause 5 includes two worked decision-rule examples and Figures 1 and 2 show acceptance zones. Annex A gives example approaches for uncertainty evaluation when results are continuous, discrete or pass/fail, including furniture-dimension and surface-test cases. Annex B explains collaborative trials and how a laboratory can compare its uncertainty or repeatability performance with a target value.

SLOVENSKI STANDARD
01-oktober-2026
Pohištvo - Splošne smernice o merilni negotovosti
Furniture - General guidelines about measurement uncertainty
Möbel - Allgemeiner Leitfaden zur Messunsicherheit
Ta slovenski standard je istoveten z: FprCEN/TS 18405
ICS:
17.020 Meroslovje in merjenje na Metrology and measurement
splošno in general
97.140 Pohištvo Furniture
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

FINAL DRAFT
TECHNICAL SPECIFICATION
SPÉCIFICATION TECHNIQUE
TECHNISCHE SPEZIFIKATION
September 2026
ICS 17.020; 97.140
English Version
Furniture - General guidelines about measurement
uncertainty
Möbel - Allgemeiner Leitfaden zur Messunsicherheit

This draft Technical Specification is submitted to CEN members for Vote. It has been drawn up by the Technical Committee
CEN/TC 207.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
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 supporting documentation.

Warning : This document is not a Technical Specification. It is distributed for review and comments. It is subject to change
without notice and shall not be referred to as a Technical Specification.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CEN All rights of exploitation in any form and by any means reserved Ref. No. FprCEN/TS 18405:2026 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Measurement uncertainty . 7
4.1 General. 7
4.2 Repeatability and reproducibility . 7
4.3 Measurement uncertainty information . 8
5 Decision rule . 8
5.1 General. 8
5.2 First example of decision rule . 8
5.3 Second example of decision rule . 9
5.4 Decision rules in case of many requirements. 10
6 Tolerances . 10
Annex A (informative) Example of measurement uncertainty evaluation . 11
A.1 General. 11
A.2 Test result is a numerical value on a continuous scale . 11
A.3 Test result is a numerical value on a discrete scale . 12
A.4 Test result is a pass/fail value . 12
Annex B (informative) Interlaboratory comparisons (collaborative trials) . 14
B.1 General. 14
B.2 Assessment of compliance of measurement uncertainty of test lab . 14
Bibliography . 15

European foreword
This document (FprCEN/TS 18405:2026) has been prepared by Technical Committee CEN/TC 207
“Furniture”, the secretariat of which is held by UNI.
This document is currently submitted to the Vote on TS.

Introduction
Standards drafted by CEN/TC 207 often involve physical quantities (e.g. forces, masses, dimensions,
angles, velocities, time) and measurement results (composed of a value and its measurement
uncertainty) associated with these quantities.

1 Scope
This document provides guidance to harmonize the expression of metrological information such as
measurement uncertainties and decision rules in standards for furniture.
This document clarifies how to deal with measurement uncertainty of measurement results, and how to
express information concerning measurement uncertainty in furniture standards.
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.
EN ISO/IEC 17025:2017, General requirements for the competence of testing and calibration laboratories
(ISO/IEC 17025:2017)
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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/
3.1
quantity
property of a phenomenon, body, or substance, where the property has a magnitude that can be
expressed as a number and a reference
[SOURCE: JCGM 200:2012, definition 1.1]
3.2
measurement uncertainty
non negative parameter characterizing the dispersion of the quantity values being attributed to a
measurand, based on the information used
Note 1 to entry: The parameter may be, for example, a standard deviation called standard measurement
uncertainty (or a specific multiple of it), or the half-width of an interval, having a stated coverage probability.
[SOURCE: JCGM 200:2012, definition 2.26]
3.3
measurement result
set of quantity values being attributed to a measurand together with any other available relevant
information
Note 1 to entry: A measurement result is generally expressed as a single measured value and a measurement
uncertainty
[SOURCE: JCGM 200:2012, definition 2.9]
3.4
expanded measurement uncertainty “U”
product of a combined standard measurement uncertainty and a factor larger than the number one
Note 1 to entry: In case of a standard distribution, using a coverage factor k = 2, the probability covered by the
interval “value ± U” is approximately equal to 95 %.
[SOURCE: JCGM 200:2012, definition 2.35]
3.5
target measurement uncertainty
measurement uncertainty specified as an upper limit and decided on the basis of the intended use of
measurement results
[SOURCE: JCGM 200:2012, definition 2.34]
3.6
repeatability condition of a measurement
condition of measurement out of a set of conditions that includes the same measurement procedure,
same operators, same measuring system, same operating conditions and same location, and replicate
measurements on the same or similar objects over a short period of time
[SOURCE: JCGM 200:2012, definition 2.20]
3.7
reproducibility condition of measurement
condition of measurement, out of a set of conditions that includes same locations, operators, measuring
systems, and replicate measurements on the same or similar objects over a short period of time
[SOURCE: JCGM 200:2012, definition 2.24]
3.8
repeatability limit “r”
value less than or equal to which the absolute difference between two test results obtained under
repeatability conditions may be expected to be with a probability of 95 %
[SOURCE: ISO 5725-1:2023, definition 3.17, modified]
3.9
reproducibility limit “R”
value less than or equal to which the absolute difference between two test results obtained under
reproducibility conditions may be expected to be with a probability of 95 %
[SOURCE: ISO 5725-1:2023, definition 3.22, modified]
3.10
decision rule
value less than or equal to which the absolute difference between two test results obtained under
reproducibility conditions may be expected to be with a probability of 95 %
[SOURCE: EN ISO/IEC 17025:2017, definition 3.7]
4 Measurement uncertainty
4.1 General
Whenever a standard refers to a quantity (3.1) to be measured, measurement uncertainty shall be
considered. The sources of measurement uncertainty are generally, but not exhaustingly:
— sampling;
— measurement method;
— equipment used;
— environmental conditions;
— operator;
— time between repeated measurements;
— place where the measurement takes place.
A portion of the measurement uncertainty may arise from repeated measurements and is therefore
influenced by the conditions under which those measurements are performed.
4.2 Repeatability and reproducibility
A distinction is made between repeatability condition of measurement and reproducibility condition of
measurement:
— repeatability condition (3.6);
EXAMPLE of repeatability condition:
One single sample measured by same operator in a single laboratory using the same measuring procedure and
same measuring system.
NOTE 1 An uncertainty derived from measurements taken under repeatability conditions, when specified in a
test method, can be used for performance evaluation. That is, an individual laboratory can assess its performance
by comparing its own measurement uncertainty with the value stated in the test method.
— reproducibility condition (3.7);
EXAMPLE of reproducibility condition:
One single sample measured by different operators in different laboratories using same measuring procedure but
different measuring systems
NOTE 2 An uncertainty derived from measurements taken under reproducibility conditions, when specified in
a test method, provides insight into the maximum expected spread of results across different laboratories or
conditions.
Measurements taken under repeatability conditions are expected to result in a smaller measurement
uncertainty compared to measurements taken under reproducibility conditions, since fewer influencing
factors vary.
4.3 Measurement uncertainty information
A standard can give information about measurement uncertainty. It is recommended that the following
information is include
...