Seat height, depth and width by seat type

At a glance

Millimetres. Seat height is floor to the top of the loaded upholstery; width is per person on a banquette or sofa; arm height is above the seat, armchairs only; 450 mm is about 17.7 inches. Basis: 'our guide' is the range in our Table heights and Banquette seating guides; 'teaching guide' is the University of Melbourne design guide; 'to confirm' means conventional practice for our partner upholsterers to confirm; HSE is the Health and Safety Executive. Design ranges, not clinical advice.

Where each dimension is measured from

Published seat dimensions disagree mainly because they are measured from different places. Fix the datum first and most of the disagreement goes away. The letters below match the drawing.

Why published numbers disagree

• Loaded or unloaded: a foam or feather seat compresses under a sitter. The height as sat on is the one that fits the table, so specify it, and give the unloaded height on the shop drawing as well.
• Frame or finished: a frame height and a finished upholstered height are different numbers. Always use the finished seat.
• Arm height from the floor or from the seat: 650 mm from the floor and 200 mm above the seat are the same arm on a 450 mm seat. Say which.
• Inside or outside width: the clear width between the arms is what a sitter has; the overall width is what the room has to find.
• Inches converted: a US figure of 17 inches becomes 432 mm. Rounded to 430 or 450 it moves the answer, so do not mix converted and native figures in one table.
• Different words for the gap above the seat: some sources give the distance from the seat to the table top, some the gap to the underside of the apron, and some a horizontal gap. The table-to-seat rule is on our Table heights sheet.

Seat heights compared

Seat height follows the surface it serves. A dining or banquette table at 720 to 760 mm pairs with a seat of 430 to 480 mm; a counter at 900 to 950 mm pairs with a stool of 600 to 680 mm; a bar at 1,000 to 1,100 mm pairs with a stool of 700 to 780 mm. The gap rules are in our Table heights guide.

In the UK, Approved Document M volume 2 (2015 edition, with the 2020 and 2024 amendments) asks that part of the working surface of a bar or serving counter is permanently usable by wheelchair users and no higher than 850 mm above the floor (paragraph 4.16b). A stool-height bar does not meet that on its own, so the accessible section is a separate detail.

Width and depth: fit the sitter, then the room

Two body measurements set the limits. Popliteal height, the floor to the back of the knee when seated, limits how high a seat can be before it presses on the thighs. Buttock-popliteal length, from the back of the pelvis to the back of the knee, limits how deep a seat can be before it presses behind the knees. The Health and Safety Executive's seating guidance puts the depth rule plainly: a seat should be deep enough to support the legs of tall people, but not so deep that shorter people cannot use the backrest.

For a seat used by the public, design for that range rather than the average, and check a full-size mock-up with the real foam and cover before production. On a banquette the unit is the diner: set out the run in places of about 550 to 600 mm centre to centre, then fit the table bases to the places, not the other way round.

Five checks before you fix a seat

• Check the upholstery build: the foam, spring and cover decide the loaded height. Ask the partner upholsterer for the loaded and unloaded height of the actual build, not a catalogue figure.
• Check arms against the table: arm height from the floor must clear the underside of the apron. A 205 mm arm on a 450 mm seat is 655 mm from the floor.
• Check depth against the back: a deeper seat reads as more relaxed, and the back angle has to be set with it. That trade-off is on the seat rake and slope sheet.
• Check the floor: heights are from finished floor level. A rug, carpet or raised floor changes the datum.
• Check access: Approved Document M gives no seat heights for dining or lounge seating. Where a project needs accessible seating, take the figures from BS 8300-2 and the project's access consultant.

Finished seat height [450] mm, tolerance [+/- 10] mm, from finished floor level to the top of the loaded upholstery on the seat centreline, one third of the depth back from the front edge; unloaded height in brackets on the shop drawing. Seat depth [430] mm, clear width between arms [480] mm, arm height [205] mm above the loaded seat.

Finished seat height [445] mm from finished floor level to the top of the loaded upholstery, with [290] mm from the seat to the top of the table. Seat depth [500] mm. Width per diner [575] mm, centre to centre, marked on the shop drawing. Confirm on a full-size mock-up of one bay.

Finished seat height [650 or 750] mm from finished floor level to the top of the loaded seat, for a surface at [925 or 1,050] mm. Seat width or diameter [400] mm. Footrest [ ] mm above finished floor level. Confirm on a sample stool at the actual counter.

Standards and sources

• Health and Safety Executive, Seating at work (HSG57), 3rd edition 1997, reprinted 2011: paras 23 to 25, Figure 1.
• Approved Document M, volume 2 (2015 edition with 2020 and 2024 amendments): paragraph 4.16, bar counters.
• University of Melbourne, Ergonomics and product interactions: teaching guide, secondary source.
• Delft University of Technology, Elementary ergonomics (open course deck): popliteal height and buttock-popliteal length.
• BS EN 16139:2025 (Annex G) and BS 8300-2:2018: named, not read.

Questions we are asked

What is the standard seat height for a dining chair?

Usually 430 to 480 mm from the floor to the top of the loaded seat, with 450 mm the common choice. A table of 720 to 760 mm pairs with it. State whether the figure is loaded or unloaded.

How deep should a chair seat be?

For a dining chair, about 380 to 460 mm. The limit is the buttock-popliteal length of a shorter sitter: a seat deeper than that presses behind the knees. Lounge seats are deeper, and the back angle has to be set together with the depth.

What is the difference between loaded and unloaded seat height?

Unloaded is the height of the seat on its own; loaded is the height with a sitter's weight compressing the foam or feather. Loaded is the figure that has to fit the table, so it is the one to specify, with the unloaded height given in brackets.

How wide should each seat be on a banquette?

About 550 to 600 mm per diner, centre to centre. Set out the places first, then position the table bases to suit the places.

What height should a bar stool be?

A counter stool is usually 600 to 680 mm for a 900 to 950 mm surface, and a bar stool 700 to 780 mm for a 1,000 to 1,100 mm bar. Set it from the surface: the seat should sit about 220 to 300 mm below the top.

Does Approved Document M give seat heights?

Not for dining or lounge seating. Volume 2 asks that part of a bar or serving counter is usable by wheelchair users and no higher than 850 mm (paragraph 4.16b). BS 8300-2 is the wider reference for accessible design.