ISO 24496:2017

INTERNATIONAL ISO
STANDARD 24496
First edition
2017-02
Office furniture — Office chairs —
Methods for the determination of
dimensions
Mobilier de bureau — Sièges de travail pour bureau — Méthodes
pour déterminer les dimensions
Reference number
ISO 24496:2017(E)
©
ISO 2017

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ISO 24496:2017(E)

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© ISO 2017, Published in Switzerland
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ISO 24496:2017(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 General measurement conditions .23
4.1 General .23
4.2 Preliminary preparation .23
4.3 Tolerances .23
4.4 Measurement uncertainty .24
5 Test equipment.24
5.1 Floor surface .24
5.2 CMD placement fixture .24
5.3 Chair measuring device (CMD) .26
5.4 High friction material .26
6 Measurement methods and procedures .26
6.1 General .26
6.2 Chair set-up and placement of CMD .26
6.2.1 Chair set-up .26
6.2.2 Initial placement of CMD on chair .27
6.2.3 Final placement of CMD on chair .29
6.3 Measuring procedures .29
6.3.1 Initial chair measurements .29
6.3.2 Measurements with the chair components adjusted to their
minimum positions .39
6.3.3 Measurements with the chair components in their maximum positions .45
6.3.4 Measurements without the CMD in the chair .45
7 Test report .48
Annex A (normative) Drawings and specifications, PDF files for CMD with 18 stacked
segment lumbar support measurement method .49
Annex B (informative) Anthropometric equivalents of terms and definitions .53
Annex C (informative) Development history and rationale .60
Bibliography .65
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ISO 24496:2017(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 on 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 the following
URL: w w w . i s o .org/ iso/ foreword .html.
This first edition cancels and replaces ISO/TR 24496:2012, which has been technically revised.
The committee responsible for this document is ISO/TC 136, Furniture.
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ISO 24496:2017(E)

Introduction
The test methods in this document are based on the manner in which anthropometric measurements
are measured.
Therefore, in order to be able to relate the dimensions of office seating to the anthropometric
dimensions, a theoretical reference seating posture has been adopted. This posture does, however, not
automatically correspond to the ideal or optimum seating posture.
The reference seating posture is as follows:
— the sole of the foot placed on the floor;
— the foot forms an angle of approximately 90° with the lower leg;
— the lower leg is approximately vertical;
— the lower leg forms an angle of approximately 90° with the thigh;
— the thigh is almost horizontal;
— the thigh forms an angle of approximately 90° with the trunk;
— the trunk is erect.
Further information on the anthropometric dimensions can be found in ISO 7250-1, ISO 20685 and
ISO 14738.
This document is meant to be used in conjunction with requirements documents. Such documents will
specify which of the dimensions are to be measured. It is possible that not all of the measurements that
can be taken by this document will be specified by the individual requirements document.
For the background and rationale for the provisions contained in this document, see Annex C.
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INTERNATIONAL STANDARD ISO 24496:2017(E)
Office furniture — Office chairs — Methods for the
determination of dimensions
1 Scope
This document specifies methods for the determination of the dimensions of office chairs.
This document does not contain dimensional specifications or requirements.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at http:// www .iso .org/ obp
NOTE For the anthropometric equivalents of the terms and definitions, see Annex B.
3.1
angle between backrest and seat
γ
angle between the loaded backrest and the loaded seat
Note 1 to entry: See Figure 1.
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Key
1 backrest
2 seat
3 CMD (Chair Measurement Device) buttocks pad
4 CMD thoracic pad
5 CMD pelvic pad
6 backrest line
γ angle between backrest and seat
Figure 1 — Angle between backrest and seat
3.2
angle – origin and sign convention
right horizontal viewed from the right side of the chair; when the user is seated in the chair and the
angle sign convention is clockwise, angle rotation is positive (+) and counterclockwise is negative (–)
Note 1 to entry: See Figure 2.
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Key
1 vertical
2 horizontal (0°)
Figure 2 — Angle – origin and sign convention
3.3
armrest height
distance from the top surface of the armrest to the bottom of the loaded CMD buttocks pad parallel to
the backrest line at a distance of 180 mm from the backrest line
Note 1 to entry: See Figure 3.
Dimensions in millimetres
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Key
1 CMD vertical member
2 armrest
3 CMD buttocks pad
4 intersection of projection of vertical member front face and armrest
5 backrest line
l armrest height
1
Figure 3 — Armrest height
3.4
armrest length
distance along the armrest within an envelope down from the top of the armrest that is 20 mm deep
Note 1 to entry: See Figure 4.
Dimensions in millimetres
Key
1 armrest
l armrest length
1
Figure 4 — Armrest length
3.5
distance between armrests
horizontal distance between armrests from the rear of the seat surface width zone forward to the front
edge of the seat within the measurement zone 5 mm down from the top of the armrest
Note 1 to entry: See Figure 5, Figure 7 and 3.28.
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ISO 24496:2017(E)

Key
1 armrest
2 rear of seat width zone
l armrest pad measurement zone
1
l distance between armrests
2
Figure 5 — Distance between armrests
3.6
front of armrest position
perpendicular distance from the backrest line to the front of the armrest that is in the measurement
zone 120 mm and greater above the top surface of the loaded CMD buttocks pad
Note 1 to entry: See Figure 6.
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ISO 24496:2017(E)

Dimensions in millimetres
Key
1 armrest
2 backrest line
3 CMD buttocks pad
4 measurement zone
l front of armrest position
1
Figure 6 — Front of armrest position
3.7
armrest width
horizontal distance across the armrest within the measurement zone 5 mm down from the top of
the armrest
Note 1 to entry: See Figure 7.
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Dimensions in millimetres
Key
1 armrest
l armrest width
1
Figure 7 — Armrest width
3.8
backrest to seat movement ratio
ratio of change of the backrest angle relative to the change of angle of the seat that occurs when a seat
and backrest move concurrently
Note 1 to entry: Does not apply to chairs with seat and/or back angles that only move independently.
3.9
backrest angle to vertical
β
angle between vertical and the loaded backrest
Note 1 to entry: See Figure 8.
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ISO 24496:2017(E)

Key
1 CMD thoracic pad
2 CMD pelvic pad
3 backrest line
4 vertical
β backrest angle to vertical
Figure 8 — Backrest angle to vertical
3.10
backrest width
smallest horizontal dimension of the backrest within the lumbar zone
Note 1 to entry: See Figure 9 and 3.18.
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Key
1 backrest
2 lumbar zone
l backrest width
1
Figure 9 — Backrest width
3.11
backrest height
distance from the loaded seat to the top of the backrest, measured parallel to the backrest line
Note 1 to entry: See Figure 10.
Key
1 backrest
2 CMD buttocks pad
3 backrest line
l backrest height
1
Figure 10 — Backrest height
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3.12
backrest inclination – range
tilt range of the backrest from its foremost inclination to its most rearward inclination
Note 1 to entry: See Figure 11.
Key
1 backrest
2 CMD thoracic pad
3 CMD pelvic pad
4 forward most tilt backrest line
5 rearward most tilt backrest line
Δ range of backrest inclination
Figure 11 — Backrest inclination – range
3.13
backrest radius – horizontal
horizontal radius of the backrest measured within the lumbar zone
Note 1 to entry: See Figure 12 and 3.18.
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Key
1 seat
2 backrest
3 lumbar zone
r horizontal radius of backrest
Figure 12 — Backrest radius – horizontal
3.14
chair measuring device
CMD
instrument for measuring dimensions of chairs
Note 1 to entry: Specified in Annex A.
3.15
hip breadth clearance
minimum horizontal distance between armrest assembly from the rear of the seat surface width
zone forward to the front edge of the armrest or armrest assembly as measured above the top of the
seat surface
Note 1 to entry: See Figure 13 and 3.28.
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ISO 24496:2017(E)

Key
1 armrest assembly
l rear of seat surface width zone to front of armrest
1
l hip breadth clearance
2
Figure 13 — Hip breadth clearance
3.16
lumbar support – height
distance from the loaded seat to the most prominent segment (or segments) of the lumbar support as
determined by the measuring indicators on the CMD, measured parallel to the backrest line
Note 1 to entry: See Figure 14 and Figure 35.
Key
1 backrest line
l height of lumbar support
1
L the most prominent segment (or segments) of the lumbar support
Figure 14 — Lumbar support – height
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3.17
lumbar support – protrusion
distance from the backrest line to the most prominent segment (or segments) of the lumbar support as
determined by the measuring indicators on the CMD, measured perpendicular to the backrest line
Note 1 to entry: See Figure 15 and Figure 35.
Key
1 backrest line
2 protrusion of lumbar support
L most prominent segment (or segments) of the lumbar support
Figure 15 — Lumbar support – protrusion
3.18
lumbar zone
area that is parallel to the backrest line, 160 mm to 270 mm above the bottom of the loaded CMD
buttocks pad
Note 1 to entry: See Figure 16.
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ISO 24496:2017(E)

Dimensions in millimetres
Key
1 lumbar zone
Figure 16 — Lumbar zone
3.19
median plane
vertical plane dividing the chair into two generally symmetrical parts (right and left)
Note 1 to entry: See Figure 17.
Key
1 median plane
Figure 17 — Median plane
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3.20
neck/head rest protrusion
perpendicular distance from the backrest line to the foremost protrusion on the neck/head rest
Note 1 to entry: See Figure 18.
Key
1 neck/head rest
2 backrest line
l neck/head rest protrusion
1
Figure 18 — Neck/head rest protrusion
3.21
neck/head rest height
distance from the loaded seat to the most prominent segment of the neck/head rest, measured parallel
to the backrest line when the neck/head rest is in its most vertical position
Note 1 to entry: See Figure 19.
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ISO 24496:2017(E)

Key
1 neck/head rest
2 backrest line
l neck/head rest height
1
Figure 19 — Neck/head rest height
3.22
seat depth
distance from the backrest line measured parallel to the CMD buttocks pad to the front of the seat
Note 1 to entry: See Figure 20.
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ISO 24496:2017(E)

Key
1 seat
2 CMD buttocks pad
3 backrest line
l seat depth
1
Figure 20 — Seat depth
3.23
seat height
vertical distance, measured at the front of the seat, from the loaded seat to the floor
Note 1 to entry: See Figure 21.
Note 2 to entry: Adjustment of the seat inclination does not constitute a change in seat height.
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ISO 24496:2017(E)

Key
1 seat
2 CMD buttocks pad
3 front of seat
l seat height
1
Figure 21 — Seat height
3.24
sitting height
vertical distance, measured 85 mm in front of the CMD backrest line, from bottom of the loaded CMD
buttocks pad to the floor
Note 1 to entry: See Figure 22.
Note 2 to entry: Adjustment of the seat inclination does not constitute a change in sitting height.
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ISO 24496:2017(E)

Dimensions in millimetres
Key
1 seat
2 CMD buttocks pad
3 backrest line
4 sitting height line marked on the CMD
l sitting height
1
Figure 22 — Sitting height
3.25
seat inclination
angle between the loaded CMD buttocks and the horizontal
Note 1 to entry: See Figure 23.
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ISO 24496:2017(E)

Key
1 CMD buttocks pad
2 horizontal
α seat inclination
Figure 23 — Seat inclination
3.26
seat surface depth
dimension of the least seat depth within the zone, 115 mm either side of the median plane
Note 1 to entry: See Figure 24.
Dimensions in millimetres
Key
1 seat
2 median plane
l seat surface depth
1
Figure 24 — Seat surface depth
3.27
seat surface width
smallest dimension of the seat surface within the seat surface width zone marked on the CMD
Note 1 to entry: See Figure 25 and 3.28.
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ISO 24496:2017(E)

Key
1 seat
l seat surface width zone
1
l seat surface width
2
Figure 25 — Seat surface width
3.28
seat surface width zone
area along the seat surface, from 125 mm forward of the backrest line to 120 mm forward of the
125 mm line that supports the user’s buttocks as marked on the CMD
Note 1 to entry: See Figure 26.
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ISO 24496:2017(E)

Dimensions in millimetres
Key
1 seat surface
2 backrest line
l seat surface width zone = 120 mm
1
Figure 26 — Seat surface width zone
3.29
under-frame — maximum off-set
maximum off-set of the under-frame is the maximum distance between the outermost point of the
under-frame including castors or glides and the axis of rotation
Note 1 to entry: See Figure 27.
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a) Under-frame without castors b) Under-frame with castors
Key
s maximum off-set of under-frame
Figure 27 — Under-frame — Maximum off-set
4 General measurement conditions
4.1 General
Caution shall be used to ensure that any chair movement, adjustments and/or applied forces do not
dislodge the CMD causing injury to the user or damage to the CMD.
4.2 Preliminary preparation
The chair shall be assembled and/or configured according to the instructions supplied with it. If
mounting or assembly instructions are not supplied, the mounting or assembly method shall be
recorded in the report.
All adjustments shall be operated through their range of adjustments at least one time before
measurements are taken.
If a measurement cannot be taken as specified in the procedures due to the design of the product, it
shall be carried out as far as possible as described, and deviations from the measurement procedure
shall be recorded in the test report.
The test shall be carried out in indoor ambient conditions. If during a test, the temperature is outside
of the range of 15 °C to 25 °C, the maximum and/or minimum temperature shall be recorded in the
test report.
4.3 Tolerances
The following equipment tolerances shall be applicable unless otherwise specified:
— Forces: specified in the relevant clauses;
— Masses:  ±1 % of the nominal mass;
— Dimensions: ±1 mm of the nominal dimension;
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— Angles: ±1° of the nominal angle.
Test masses, forces, dimensions and angles shall be targeted at the nominal values specified.
4.4 Measurement uncertainty
The measurement uncertainties according to Table 1 shall be applicable unless otherwise specified.
A rationale explaining the background of the measurement uncertainty is contained in C.6.
Table 1 — Measurement uncertainty
Uncertainty at 95 % confidence
Clause no. Measurement description
level (k = 2)
6.3.1.1 Lumbar support horizontal protrusion ±15 mm
6.3.1.1 Lumbar support vertical height ±25 mm
6.3.1.2 Seat angles ±2°
6.3.1.2 Backrest angles ±4°
6.3.1.2 Backrest to seat angles ±4°
6.3.2.2 or 6.3.3.2 Seat height ±8 mm
6.3.2.2 or 6.3.3.2 Sitting height ±15 mm
6.3.2.3 or 6.3.3.3 Seat depth ±25 mm
6.3.2.4 or 6.3.3.4 Backrest height ±15 mm
6.3.2.5 or 6.3.3.5 Front of armrest position ±40 mm
6.3.2.7or 6.3.3.6 Armrest height ±10 mm
6.3.4.2 Seat surface width ±10 mm
6.3.4.3 Seat surface depth ±25 mm
6.3.4.4 Backrest width ±10 mm
a
6.3.4.5 Backrest horizontal radius N.A.
6.3.4.6 Armrest length ±5 mm
6.3.4.7 Armrest width ±5 mm
6.3.4.8 Hip breadth clearance ±20 mm
6.3.4.9 Distance between armrests ±60 mm
6.3.4.10 Offset of the underframe ±8 mm
a
N.A. = not applicable
5 Test equipment
5.1 Floor surface
A rigid, horizontal and flat surface.
5.2 CMD placement fixture
A fixture which holds the chair in position while applying the horizontal force and lowering the CMD
into the chair. This device shall not prevent adjustment of the chair. An example of the device (or
devices) is shown in Figure 28 and Figure 29.
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Key
1 CMD lowering crane
2 horizontal force loading device [see 6.2.2 e)]
3 chair base restraint mechanism
Figure 28 — Example of CMD placement fixture without chair
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Key
1 CMD lowering crane
2 horizontal force loading device [see 6.2.2 e)]
3 chair base restraint mechanism
4 CMD
Figure 29 — Example of CMD placement fixture with chair and CMD
5.3 Chair measuring device (CMD)
The device is specified in Annex A.
5.4 High friction material
Friction cloth for placing between the seat and the CMD in order to prevent the CMD from sliding on the
seat during measurements. It can be, for example, an anti-slip material used underneath carpets. The
thickness of the material, when compressed by the CMD, shall not exceed 1 mm.
6 Measurement methods and procedures
6.1 General
The measurements shall be taken to determine the dimensions and angles of the chair.
After the chair set-up and the CMD placement (6.2), the measurements shall be taken as specified in the
measurement procedures (6.3).
6.2 Chair set-up and placement of CMD
6.2.1 Chair set-up
a) Position the chair on the floor surface (5.1) with the seat in the highest position.
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b) Adjust all of the following to the mid-position of their range: seat depth, back rest tilt tension, back
rest height, and lumbar devices. If an exact mid-position is not possible, then set the adjustable
element to its next greater position. If there are independently adjustable lumbar device(s), adjust
the height to the approximate midpoint of the lumbar adjustment range, then adjust the protrusion
to its mid-position, if that can be done without altering the height setting.
c) Adjust the seat so that it is in an approximately horizontal position that is counterclockwise of the
horizontal without forcing the functions of the chair. If the chair has no position counterclockwise
of the horizontal, set at most horizontal position without forcing the functions of the chair.
d) If independently adjustable, position the backrest so that the support surface is approximately
vertical. If the adjustment of the backrest to a vertical position will change the seat inclination, the
horizontal seat position shall take precedence.
e) Mark a line in the centre of the backrest so that the mark is visible from the top of the backrest.
Place marks on either side of the seat 182 mm from the seat’s centre near the front of the seat to
assist in placing the CMD centrally in the chair.
6.2.2 Initial placement of CMD on chair
a) Load the CMD according to Annex A.
b) Place a layer of high friction material (5.4) between the CMD and the seat in order to ensure that
the CMD does not slide on the seat.
c) The vertical member of the CMD shall be locked at 90° until step g) of 6.2.2 (see Figure 30).
Key
1 CMD vertical member to buttocks lock
Figure 30 — CMD vertical member locked
d) Place and attach the chair in the CMD placement fixture (5.2), so that CMD vertical member is close
to, but not touching, the chair’s backrest.
e) Ensure the CMD, chair and chair fixture are in alignment with the median plane. Ensure that the
CMD buttocks pad is as horizontal as possible. Place the CMD seat depth indicator at a position that
will be near, but not in contact with, the front edge of the seat as the CMD is lowered on to the chair.
Lower the CMD until it is just above seat (no part of the CMD shall touch the seat) and just in front of
the back rest (see Figure 31).
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Figure 31 — CMD hovering above chair
f) Push the CMD towards the backrest with a force F of (40 ± 2) N (see Figure 32).
Key
F force of (40 ± 2) N
Figure 32 — Installation fixture force application
g) With this force acting, lower the CMD on to the seat while maintaining CMD alignment with the
median plane. Use the previously loc
...