A booth is fixed millwork, so its dimensions are decided once
A loose chair can be swapped between rooms. A booth cannot. The seat platform, the back panel, the plinth and the table fixing are one assembly, and the table is usually anchored to the floor or to the booth itself. Once that unit is on site and levelled, the seat height is no longer a design decision, it is a fact.
That is why booth numbers belong on the drawing stage, next to the door swings and the sprinkler drops. Four figures drive the whole assembly: finished seat height, seat depth, back height and the height of the table top above the seat. Each has a working range, and each produces a specific complaint when it falls outside that range.
The complaints are predictable. A seat set too low under a fixed 750 mm top pushes the guest's thighs up against the apron and they sit with their knees apart. A seat set too deep in front of a fixed back leaves shorter guests perched on the front edge with nothing behind them. A back rail under 900 mm in a long run gives no acoustic separation, so a forty-cover room reads as loud as a sixty-cover one. None of these are upholstery problems, and no amount of better foam fixes them. This is why a run of restaurant booth seating should be specified from the seat outwards, not from a photograph inwards.
Seat height: 450 mm finished, and why 430 mm usually fails
The working figure for a full-service dining booth is 450 mm to the finished, compressed seat surface. Loose dining chairs sit in the same band, 450 to 460 mm, which is what makes a mixed room feel consistent when a guest moves from a booth to a chair at the next table.
The temptation is to specify 430 mm because a lower seat reads as more relaxed in a render. It does not survive contact with a standard table. A dining top is normally 750 mm high, and with a 25 mm top plus a 40 mm apron the underside sits at about 685 mm. At a 450 mm seat that leaves 235 mm of clear thigh space; drop the seat to 430 mm and you gain 20 mm of clearance but lose the elbow line, because the guest's forearms now sit above the table edge and every plate has to be reached upwards.
The number that matters is the finished height, not the frame height. A 40 mm foam seat cushion compresses 8 to 12 mm under an adult, so a frame built at 460 mm lands at 448 to 452 mm in use. Write the requirement as 450 mm finished and compressed on the drawing, and check it after upholstery rather than at frame stage. If the seat is a spring unit rather than foam, expect 12 to 15 mm of settle in the first month and set the frame 10 mm high to compensate.
Seat depth and back rake: where usable depth disappears
Seat depth for a booth runs 480 to 520 mm from the front edge of the seat to the face of the back. The upper end of that range suits tall guests and long dwell times; the lower end suits rooms where the table edge sits well over the seat and the guest is expected to lean forward.
Usable depth is not the same as built depth. If the table top overhangs the seat by 40 mm, the guest loses 40 mm of legroom before they sit down. A 500 mm seat with a 40 mm overhang behaves like a 460 mm seat, which is tight for anyone over 180 cm. On banquet seating where the table is fixed to the booth, measure from the seat front to the table edge, not to the back panel, and keep that clear distance at 460 mm or more.
Back rake is the second hidden variable. An 8 to 12 degree rake from vertical is comfortable and keeps the head over the hips. Push it to 15 degrees and a 480 mm seat delivers less usable depth than a 450 mm seat at 10 degrees, because the guest slides forward to keep their back supported. Back height is a separate decision from rake: 900 mm above the floor keeps sightlines open across the room, 1050 to 1200 mm gives separation between covers, and anything above 1200 mm turns the top rail into a headrest that tall guests will lean on, so the run then needs a wall fixing every 600 mm rather than every 900 mm. A pair of facing booth and banquette sets at 1100 mm back height is the configuration most full-service rooms settle on, because it separates covers without closing the room.
Table overhang and the 600 mm rule
Allow 600 mm of table edge per cover on a booth run. Four covers facing each other across a fixed table need 2 x 600 mm plus a 100 mm centre gap for the condiment tray and the pass-through, which is 1300 mm of table length. Cutting that to 1200 mm to fit a bay is the single most common cause of elbow collisions in a booth, and it is invisible on a plan.
Overhang past the base or plinth should be 30 to 50 mm on the booth side so knees clear the support, and 25 to 50 mm on the open side. Under 25 mm and guests knock their knees on the frame; over 50 mm and the overhang starts to act as a lever on the base, which is where a table begins to rock after a year of guests leaning on the edge.
Table depth for two facing rows runs 700 to 800 mm. A 600 mm deep top looks efficient on a plan and fails in service once plates, a water jug and a bread basket share the surface. Where the top is solid timber, keep the thickness at 30 to 40 mm so the span between supports does not sag; a 25 mm top over a 1300 mm span will bow 2 to 3 mm within two years, and that bow is visible against a straight booth back. The same rule applies to solid wood dining tables used as loose tables in the middle of the room, where the span is often longer than in a booth.
Fixed-to-loose ratio and the aisles that follow from it
Most full-service rooms run 55 to 65 percent of covers on fixed seating. Fixed covers turn faster because the guest cannot push the seat back and take up more floor, and the room reads as busier at the same occupancy. Below 50 percent the room loses that density; above 70 percent the floor plan has no flexibility for a party of five or a guest with a stroller.
Each fixed seat consumes 450 to 500 mm of depth per side, and that depth is not negotiable, because it is the seat plus the back panel plus the small gap behind it. Two facing rows plus a 750 mm table therefore occupy about 1700 mm of floor depth. A chair-and-table pair doing the same job occupies 1900 to 2000 mm once the chair is pulled out, which is where the density gain comes from.
Aisles are set by the fixed rows, not by the loose ones. A 900 mm clear aisle between a booth edge and the next table is the minimum for a member of staff carrying a tray; 1050 to 1200 mm is what a room should have on the main run. Behind a booth back, allow 1100 mm if staff pass with a tray, because the back panel gives them nothing to step around. These figures are why restaurant furniture layout planning has to happen against the actual bay dimensions rather than against a nominal covers-per-square-metre target.
Floor levelling and anchoring
Booths sit on a plinth 100 mm high, recessed 50 mm from the seat front so feet do not kick it. Pack the plinth at 600 mm centres with shims, and hold the run to a tolerance of 3 mm over any 3 m. On a floor that falls 8 mm across a 6 m run, a booth built level will show a gap under one end that no amount of sealant hides.
Anchor into the structural slab, not into the screed. An 8 mm wedge anchor at 800 mm centres through the plinth into the slab is enough for a fixed run; anchors that only bite the screed pull out within a season once guests use the back rail to push themselves up. Where underfloor services run beneath the booth line, use a resin anchor at reduced depth and mark the positions on the drawing so the next contractor does not drill through a conduit.
Check level after upholstery as well as before. A 40 mm cushion compressed on one side of a run and not the other will make a level booth feel uneven, and the fix at that stage is shimming the seat platform, which means removing the seat panel. Levelling is cheap before the panels go on and expensive afterwards.
What to write on the drawing
A booth drawing that can be built without a phone call carries: finished seat height with the compression note, seat depth from front edge to back face, back height above finished floor, back rake in degrees, table top height, table length and depth per cover, overhang on both sides, plinth height and recess, anchoring specification, and the floor tolerance. Add the bay width and the wall it fixes to, because a booth that is 10 mm wide of its bay has to be remade.
Two models show how those numbers land in production. The solid wood booth set is built on a 450 mm finished seat with a 1100 mm back and a timber plinth, and it is quoted against the bay width rather than a stock size. The metal booth set uses a welded steel frame with a 40 mm foam seat over plywood, which holds its 450 mm height better in high-turnover rooms because the frame does not compress. For rooms that want a lower back and a softer line, the korean solid wood booth set runs a 900 mm back with an 8 degree rake.
Whichever model you choose, send the bay dimensions and the floor tolerance with the enquiry. A booth quoted from a photograph and built to a stock size is the reason most booth complaints are about fit rather than about materials.