Office Chair Seat Height Standard: EN 1335 vs BIFMA

The office chair seat height standard your European buyer is checking is not one number — it is a table with four chair types, and a chair that lands outside the type you declared gets stopped at document review, long before the container is booked. EN 1335-1 sets those dimensions. ANSI/BIFMA X5.1 does not set any. Suppliers who answer "seat height 45–55 cm" and stop there are answering a question nobody asked.

Here is the table your buyer is reading, what each column means, and the four lines that belong on your spec sheet.

The office chair seat height standard: all four types at a glance

EN 1335-1:2020, Office furniture — Office work chair — Part 1: Dimensions — Determination of dimensions, specifies dimensions for chair types Ax, A, B and C, plus the method for measuring them. Type Ax and Type A carry the most adjustment; Type C the least. The standard does not call one type better than another — it labels how much adjustment the chair offers, which is exactly what a procurement officer needs to know before comparing two quotes.

All values below are millimetres, taken from Table 2 of EN 1335-1:2020.

Adjustable dimensions

Dimension (adjustable)	Type Ax	Type A	Type B	Type C
Seat height / sitting height	400–540, min. range 160	400–520, min. range 130	420–510, min. range 100	430–480, min. range 80
Depth of the seat	380–430, min. range 70	425–450, min. range 70	425–445, min. range 50	from 425, no min. range stated
Height of lumbar support	170–300, min. range 70 within the range	170–300, min. range 70 within the range	170–300, min. range 50 within the range	170–300, no min. range stated
Clear distance between armrest pads	410–510	410–510	460–510	460–510
Height of armrests	200–290, min. range 100	200–290, min. range 100	225–250, min. range 50	200–250, no min. range stated

Fixed alternatives and outer limits

Dimension	Type Ax	Type A	Type B	Type C
Fixed seat depth	not permitted	not permitted	425–485	from 425
Fixed lumbar support height	not permitted	not permitted	170–300	170–300
Fixed distance between armrest pads	not permitted	not permitted	460–510	from 460
Fixed armrest height	not permitted	not permitted	225–275	200–250
Max. distance, backrest to front of armrests	≤ 200	≤ 300	≤ 350	≤ 400
Hip breadth clearance, armrests at widest	≥ 480	≥ 480	≥ 460	≥ 460
Seat pad width	≥ 400	≥ 400	≥ 400	≥ 400
Seat pad depth	≥ 380	≥ 380	≥ 380	≥ 380

How to read the columns without guessing

Table 2 gives each dimension four things, not two: a min value, a max value, whether the chair is allowed to go below the min, whether it is allowed to go above the max, and — for adjustable dimensions — a minimum adjustment range.

That last column is the one suppliers skip, and it is the one that decides the type. Two chairs can both offer "seat height 420 to 500 mm." Only one of them is Type A material, because Type A wants at least 130 mm of travel and that chair has 80. The window and the travel are separate requirements, and a chair has to satisfy both.

Read it as a plain sentence: "Type A seat height: the adjustment has to work inside the 400–540 mm neighbourhood and give the user at least 130 mm of travel; going below 400 or above 520 is permitted, not required." Where the standard says a dimension is fixed rather than adjustable, Ax and A simply do not allow it — a fixed seat depth is a Type B or Type C feature, full stop.

The office chair seat height standard is a range plus a travel figure, not a single measurement. Quote both or you have quoted neither.

The four lines that get a chair rejected

Field pattern, from quotes that come back with questions:

Seat height quoted from the floor to the top of the cushion, uncompressed. EN 1335-1 defines the measurement method as well as the number — Part 1 is literally titled "Determination of dimensions." A 20 mm difference in where you put the tape moves a chair across a type boundary.
Armrest height quoted, armrest spacing omitted. The clear distance between armrest pads has its own limits — 410–510 mm for Ax and A, 460–510 mm for B and C — and the fixed variant is only permitted on B and C. Buyers who specify Type A and receive fixed armrests reject on the spot.
Seat pad width and depth treated as "about right." These are floors, not ranges: ≥ 400 mm wide and ≥ 380 mm deep, identical across all four types. There is no type where a 370 mm deep pad passes.
The distance from the backrest to the front of the armrests, never mentioned. It is a maximum — 200 mm for Ax rising to 400 mm for Type C — and it is the dimension most catalogue sheets have never heard of.

If you sell seating into Europe alongside other furniture, the same discipline applies one category over: see how counter height vs bar height stools breaks on exactly this kind of unstated measuring convention.

BIFMA answers a completely different question

North American buyers ask about BIFMA, and suppliers often assume it is the American EN 1335. It is not.

ANSI/BIFMA X5.1, General-Purpose Office Chairs (2017 edition) is a performance and durability test standard. It defines a battery of tests — backrest strength, seat drop impact, arm strength, stability and more — that a chair must survive. It does not hand you a millimetre table.
BIFMA G1-2013, the Ergonomics Guideline for furniture used in office work spaces designed for computer use, is a guideline, and its condensed "Ultimate Test for Fit" is written as fit criteria in words rather than numbers: users "should be able to sit with their feet comfortably on the floor or footrest without undue pressure on the underside of the thighs," the torso-to-thigh angle "should not be less than 90°," the seat should be wide enough not to limit armrest use. Real ergonomic criteria — zero prescribed dimensions.
On the European side, the split is deliberate: EN 1335-1 is dimensions, EN 1335-2 is safety, strength and durability requirements (built around 8 hours of daily use by persons weighing up to 110 kg), and EN 1335-3 is the mechanical test methods for stability, strength and durability.

EN 1335-1 tells you what the chair must measure; BIFMA X5.1 tells you what the chair must survive. A chair can pass every X5.1 test and still miss EN 1335-1 Type A on adjustment travel alone. Declaring "BIFMA tested" to a German buyer answers a durability question they did not ask and leaves the dimensional one open.

What belongs on the spec sheet, and what belongs on the image

Two different jobs, and suppliers usually do only the first one badly.

On the spec sheet, four lines. Every one of them ties back to the office chair seat height standard and its neighbours in Table 2:

Field	Write it like this
Type declaration	Conforms to EN 1335-1:2020, Type A
Seat height	420–520 mm adjustable (travel 100 mm), measured per EN 1335-1
Seat pad	480 mm wide × 430 mm deep
Armrests	Height 200–290 mm adjustable; clear distance between pads 410–510 mm

On the image, the same numbers where the eye lands. A buyer comparing five quotes does not open five PDFs — they scan five photos. A chair photo carrying the seat-height range, the seat pad width and depth, and the armrest spacing as callouts answers the whole first round of questions before it is asked. The catch is that those callouts have to be right: a number drawn on by hand or invented by an image generator looks identical to a measured one and is worth nothing when the buyer's inspector puts a tape on the sample. Software that snaps to the product's real edges, converts against a known reference, and exports at the size each marketplace or catalogue wants gives you a diagram whose numbers survive contact with an inspection report. That is the difference between a picture of a chair and a furniture spec diagram.

For the underlying reference figures buyers compare against, the standard office chair dimensions page carries the common ranges by chair class. The same "publish the number, not the adjective" logic drives sofa dimensions for export.

Pre-quote checklist

Type declared (Ax / A / B / C) with the edition — "EN 1335-1:2020", not "EN 1335"
Seat height given as a window and an adjustment travel figure
Measuring convention stated (per EN 1335-1, uncompressed, floor to seat surface)
Seat pad width ≥ 400 mm and depth ≥ 380 mm confirmed on the production sample, not the prototype
Armrest height range and clear distance between pads both listed
Fixed vs adjustable stated for seat depth, lumbar height and armrests — fixed rules out Ax and A
Backrest-to-armrest-front distance checked against the type maximum
Separate line for EN 1335-2 / EN 1335-3 test reports if the buyer asked for durability, not dimensions
BIFMA X5.1 report offered as a durability answer, never as a dimensional one
The same numbers appear on the product image, not only in the PDF

FAQ

What is the standard seat height for an office chair in Europe?

There is no single figure. EN 1335-1:2020 defines it per chair type: 400–540 mm for Type Ax, 400–520 mm for Type A, 420–510 mm for Type B and 430–480 mm for Type C, each with a minimum adjustment range (160, 130, 100 and 80 mm respectively). Quoting one number without the type is why buyers come back with questions.

What is the difference between EN 1335 Type A, Type B and Type C?

Adjustment. Type Ax and Type A require adjustable seat depth, lumbar height and armrests, with the widest travel; Type B allows fixed versions of several of those dimensions within stated limits; Type C allows the most fixed features and the narrowest seat-height travel (80 mm). Declaring the wrong type is a specification error, not a quality complaint.

Does BIFMA specify office chair dimensions?

No. ANSI/BIFMA X5.1 is a performance and durability test standard for general-purpose office chairs, and BIFMA G1-2013 is an ergonomics guideline written as fit criteria rather than millimetre limits. If a North American buyer needs dimensional conformity, they have to name a dimensional standard — X5.1 will not give it to them.

How should seat height be measured for a spec sheet?

Per the method in EN 1335-1, which is why the title of Part 1 includes "Determination of dimensions." Measure to the seat surface with the chair unloaded unless the standard's procedure states otherwise, and say on the sheet which convention you used. An unstated convention is the most common source of a 15–25 mm discrepancy between your figure and the buyer's inspection report.

Can one chair be certified to both EN 1335 and BIFMA?

Yes, and many are — they test different things, so the reports stack rather than conflict. What you cannot do is substitute one for the other on a spec sheet: the EN 1335-1 line answers "what size," the X5.1 line answers "how tough."

Office Chair Seat Height Standard: Four Types, Four Ranges