SIST-TS CEN/TS 18231:2026

SLOVENSKI STANDARD
01-april-2026
Pohištvo - Vodilo za merjenje mer po EN 1335-1 z uporabo ISO 24496 (CMD)
Furniture - Guide to measuring EN 1335-1 dimensions with ISO 24496 CMD
Möbel - Leitfaden für die messung der abmessungen nach EN 1335-1 mit ISO 24496
Mobilier - Guide pour mesurer les dimensions EN 1335-1 avec le CMD ISO 24496
Ta slovenski standard je istoveten z: CEN/TS 18231:2026
ICS:
97.140 Pohištvo Furniture
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

CEN/TS 18231
TECHNICAL SPECIFICATION
SPÉCIFICATION TECHNIQUE
January 2026
TECHNISCHE SPEZIFIKATION
ICS 97.140
English Version
Furniture - Guide to measuring EN 1335-1 dimensions
with ISO 24496 CMD
Mobilier - Guide pour mesurer les dimensions EN Möbel - Leitfaden zur Bestimmung der Maße nach EN
1335-1 avec le CMD ISO 24496 1335-1 mit ISO 24496 CMD
This Technical Specification (CEN/TS) was approved by CEN on 14 December 2025 for provisional application.

The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to
submit their comments, particularly on the question whether the CEN/TS can be converted into a European Standard.

CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS
available promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in
parallel to the CEN/TS) until the final decision about the possible conversion of the CEN/TS into an EN is reached.

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.
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. CEN/TS 18231:2026 E
worldwide for CEN national Members.

Contents Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Guidance for chair setup and placement of CMD on chair . 6
4.1 Chair set up . 6
4.2 Final placement of CMD on chair . 8
4.3 Further preparatory steps . 9
5 Guidance on measuring procedures . 10
5.1 General. 10
5.2 Measurements with the chair components adjusted to their middle position . 10
5.2.1 Sequence 1 - Lumbar support maximum height: fmax . 10
5.2.2 Sequence 2 - Lumbar support minimum height: fmin . 10
5.2.3 Sequence 3 - frange . 10
5.2.4 Fixed height lumbar support . 10
5.2.5 Determination of angles γ, e and l . 11
5.2.6 Sequence 4 - Angle between seat and back: ɤ . 11
5.2.7 Sequence 5 - Angle backrest inclination range: l . 11
5.2.8 Sequence 6 - Seat pad angle adjustable and seat pad angle fixed - minimum: e (min) . 12
5.2.9 Sequence 7 - Seat pad angle adjustable and seat pad angle fixed – maximum: e (max) . 12
5.3 Measurements with the chair components adjusted to their minimum position . 12
5.3.1 General. 12
5.3.2 Sequence 8 - Seat height: a (min) . 12
5.3.3 Sequence 9 - Sitting height: a (min.)(see Figure 7) . 13
5.3.4 Sequence 10 - Adjustable depth of the seat / Fixed depth of the seat: b (min.)(see Figure 8)
............................................................................................................................................................................. 14
5.3.5 Sequence 11 - Backrest height: h (min.) . 14
5.3.6 Sequence 12 - Maximum distance from the backrest to the front of the armrests: q (max)
............................................................................................................................................................................. 15
5.3.7 Sequence 13 - Height of armrests adjustable / Height of armrests not adjustable: p (min)
............................................................................................................................................................................. 16
5.4 Measurements with the chair components adjusted to their maximum position . 16
5.4.1 General. 16
5.4.2 Sequence 14 - Seat height: a (max.) . 17
5.4.3 Sequence 15 - Sitting height: a (max.) . 17
5.4.4 Sequence 16 - Adjustable depth of the seat / Fixed depth of the seat: b (max.) . 17
5.4.5 Sequence 17 - Backrest height: h (max.) . 17
5.4.6 Sequence 18 - Height of armrests adjustable / Height of armrests not adjustable: p (max.)
............................................................................................................................................................................. 17
5.5 Measurements without the CMD on the chair . 17
5.5.1 General. 17
5.5.2 Sequence 19 - Seat pad width: d . 17
5.5.3 Sequence 20 - Seat pad depth: c . 17
5.5.4 Sequence 21 - Backrest width: j . 18
5.5.5 Sequence 22 - Radius of backrest: k . 18
5.5.6 Sequence 23 - Armrest length: n (see Figure 13) . 18
5.5.7 Sequence 24 - Armrest width: o (see Figure 14) . 19
5.5.8 Sequence 25 - Maximum clearance between armrest assembly when armrests are in their
widest position: r . 19
5.5.9 Sequence 26 - Adjustable clear distance between armrest pads / Fixed clear distance
between armrest pads: z . 20
5.5.10 Sequence 27 - Offset of the underframe: s . 20

European foreword
This document (CEN/TS 18231:2026) has been prepared by Technical Committee CEN/TC 207
“Furniture”, the secretariat of which is held by UNI.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to announce this Technical Specification: 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 the
United Kingdom.
Introduction
This document provides guidance information on how to measure the dimensions from
EN 1335-1:2020+A1:2022 by using test methods and the chair measuring device (CMD) in
ISO 24496:2021.
They have been drawn up by a working group of experts set up by CEN/TC 207/WG3 with the prime
objective to give clear guidance on how to take measurements and avoid interpretations. This can
minimize the discrepancies between dimensions taken by different groups of measurers.
This document can be used alongside ISO 24496:2021 when determining how to take the dimensions of
the office chair.
ISO 24496:2021 and this document might not cover all situations and designs. When a measurement
cannot be taken as specified in the procedures due to the design of the product, it can be carried out as
far as possible as described, and deviations from the measurement procedure can be recorded in the test
report.
1 Scope
This document explains how to act and avoid interpretations on how to measure the dimensions of
EN 1335-1:2020+A1:2022 using the test methods and chair measurement device (CMD) of
ISO 24496:2021.
This document provides additional information not provided in ISO 24496:2021, further clarifications
and examples to make measurement of the dimensions more precise and less interpretable.
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 1335-1:2020+A1:2022, Office furniture — Office work chair — Part 1: Dimensions — Determination of
dimensions
ISO 24496:2021, Office furniture — Office chairs — Methods for the determination of dimensions
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 1335-1:2020+A1:2022 and
ISO 24496:2021 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 Guidance for chair setup and placement of CMD on chair
4.1 Chair set up
For facilitating the measuring procedures, the chair will be set up before the CMD placement - reference
lines are recommended to be marked on the chair as shown in Figure 1 [ISO 24496:2021, 6.2.1].
Dimensions in millimetres
Key
1 backrest
2 seat
3 median plane
4 lumbar zone
5 seat surface width zone
6 help for CMD placement
7 seat depth line
NOTE 200 mm tape can be placed on the seat pad to transfer seat pad width zone from the CMD, so that seat
pad width can be measured at sequence 19.
Figure 1— Useful lines to be marked on the chair
Before placing the CMD on the chair:
— All adjustments shall be operated through their range of adjustments at least one time before
measurements are taken.
— Adjust all of the following to the mid-position of their range: seat depth, backrest tilt tension, backrest
height, and lumbar devices. If an exact mid-position is not possible, then set the adjustable element
to its next greater position [ISO 24496:2021, 6.2.1 b].
4.2 Final placement of CMD on chair
At this stage, it shall be ensured that CMD is hanging on the gantry with buttocks plate (base)
approximately horizontal. The CMD may have adjustable turnbuckles (or other suitable means) to enable
the operator to level CMD’s base in the median and transversal planes.
Set the horizontal force loading device on the gantry to a height that the loading force can still act on the
CMD during the final lowering stage. A horizontal force of 40 N is applied to the CMD by means of the
horizontal force loading device and the CMD is slowly lowered into the swivel chair; the seat depth gauge
shall not touch the seat. Estimate, or manually try, how far the CMD is likely to be pushed backwards
(40 N). This is how far the seat depth gauge should be from the front edge of the seat, otherwise it could
prevent the CMD from moving fully to the backrest (see Figure 3).

Figure 2 — Examples of lines on the CMD to assist centring the CMD in the chair
NOTE 1 On the CMD, it is possible to find different lines which help to place the CMD on the chair and ensure that
it is centred as shown in Figure 2.
It is recommended that CMD should be placed on the chair by two people to ensure that the CMD is
centred on the chair.
Check again whether the seat depth slider is equally close to the seat pad on the right and the left side of
the chair (see Figure 3).
Check that the pelvic or thoracic element is in contact with the backrest (see Figure 3).
Key
1 pelvic or thoracic shall be in contact with the backrest
2 small gap
Figure 3 — Placement of the CMD on the chair
NOTE 2 This can require removal and re-placing of the CMD.
If any adjustments to the chair were made, relock the vertical member at 90°, remove the CMD and follow
th
...