Ergonomic office chair (task chair)

01

Check the seat height and depth ranges

The University of California's ergonomic requirements for task chair purchases (updated June 2015), based on ANSI/HFES 100-2007 and ANSI/BIFMA, require seat height to adjust at least 4.5 in within 15–22 in from the floor; seat depth preferably adjustable over up to 3 in including a 16.9 in depth, or no deeper than 16.9 in if fixed; a seat pan at least 17.7 in wide with a rounded front edge; a five-leg base with casters for the floor type; and weight capacity of at least 250 lb, preferably 275 lb. [1]

CCOHS, Canada's occupational health and safety centre, gives a rule of thumb that optimal seat height is about one quarter of body height, says users should sit with feet on the floor or a footrest without pressure under the thighs, and recommends a five-point base for stability. [3] OSHA's computer workstation eTool asks for a seat that is height-adjustable, especially when shared, padded with a rounded 'waterfall' edge, and depth-adjustable so the front edge does not touch the back of the knee. [2]

Editorial calculation: 15–22 in is 381–559 mm and a 4.5 in stroke is 114 mm; 16.9 in is about 429 mm; 250 and 275 lb are about 113 and 125 kg. By CCOHS's rule, users 1.60 m and 1.90 m tall would want seats near 400 and 475 mm. [1] [3]

Give the supplier the user population (height and weight range), task and desk height, floor type, seat height and depth ranges required, recline and lumbar adjustment, armrest adjustment, upholstery and cleaning needs, standards and test reports (e.g. ANSI/BIFMA X5.1, EN 1335), warranty and quantities.

02

Check backrest recline, lumbar position and armrests

OSHA asks for a backrest that follows the spine's natural curve with a height-adjustable lumbar support, a recline of at least 15° from vertical that locks or has adjustable tension, and armrests, if fitted, that let the shoulders relax with elbows close to the body. [2]

The UC requirements specify a backrest top at least 17.7 in above the seat and at least 14.2 in wide, lumbar support adjustable within 5.9–9.8 in above the seat, backrest recline of 15° or more between 90° and 120° (with a headrest above 120°), angle lock with adjustable resistance, and armrests adjustable within 6.7–10.6 in above the seat with at least 18.1 in between them. [1] CCOHS adds that armrests may need to be adjusted or removed if they stop the user sitting close to the desk. [3]

Editorial calculation: in metric, the UC lumbar zone of 5.9–9.8 in is about 150–249 mm above the seat, armrest heights of 6.7–10.6 in are about 170–269 mm, and the 14.2 in minimum backrest width is about 361 mm. [1]

03

Compare a maker's user-weight rating and recline stops with procurement minimums

Steelcase's product page for its Leap task chair states that the chair is durable enough for users up to 400 lb, that the Leap stool is rated to 300 lb, and that the Leap Plus version supports users up to 500 lb with the same functions. The recline range includes full recline with four recline-angle stop settings and an upright back lock, and the back resistance is set manually. Lumbar support is height-adjustable as standard with a separate lower-back firmness control; the LiveBack backrest is designed to change shape with the spine, and the Natural Glide System moves the seat forward as the user reclines so the distance to the work surface stays the same. Arms are offered as armless or height-adjustable with further adjustable options, and the adjustment labels are in English and Braille. [4]

Editorial calculation: 400 lb is about 181 kg, 500 lb about 227 kg and 300 lb about 136 kg, compared with the University of California minimum of 250 lb (113 kg), preferably 275 lb (125 kg). Four recline stops plus an upright lock meet the OSHA guidance of a backrest that reclines and can be locked; when buying, ask for the user-weight rating with its test basis (such as ANSI/BIFMA), the recline angle at each stop, and the measured lumbar and seat-depth ranges. [4] [1] [2]

04

Compare what suppliers offer

Suppliers linked to this page list ergonomic office or task chairs; each card links to the page reviewed.

Listings include task chairs, executive and conference seating and complete office furniture ranges; ask each for the measured adjustment ranges and the weight rating test report of the model offered.

05

Trace the chair components

This is a functional reference built from the sources cited; it is not one maker's specification.

06

Fill the specification fields with values for your parts

A task chair quotation needs values for your users. The table explains each field, gives published values where a reviewed source states them, and says what to obtain from the supplier.

07

Send the user, adjustment and testing data together

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Users: [height range; weight range; shared or personal]
Seat: [height range; depth range; width]
Back: [recline; lock; lumbar range]
Arms: [height; width; removable]
Base: [five-leg; castors for floor]
Materials: [upholstery; cleaning]
Testing: [ANSI/BIFMA X5.1; EN 1335; reports]
Supply: [quantity; warranty; delivery]

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