Interior sizes by country

Sizes vary by country in three distinct ways, and it is worth sorting any question into the right one before looking up a number. Some things interchange freely, because they are sized from the human body and bodies do not vary by border. Some things nearly interchange, because two manufacturing modules ended up within a few per cent of each other, and those are the expensive ones. Some things do not interchange at all, because a national code or a service connection fixes them. Work down that list in order and most cross-border problems answer themselves before a tape comes out.

Beds: the near-misses that cost most#

Mattresses are the clearest example of the middle category, because the names collide as badly as the sizes.

A UK king and a US queen are 2 cm apart in width and 3 cm in length. A fitted sheet stretches over that and a mattress protector mostly does, so the error is not discovered at the shop or on the first night. It is discovered by the duvet, which is sized to a different family entirely, and by the frame, which is not. The full chart including bedding compatibility is in bed sizes by country, and the room each size actually needs, which is the number people skip, is in bed sizes and the room each one needs.

Kitchens: 600 mm against 24 in#

Kitchen carcasses are where the two systems diverge most visibly and where the money is. A European base unit is 600 mm wide and 560 to 600 mm deep on a 720 mm carcass with a 150 mm plinth. A US base cabinet is 24 in (610 mm) wide and deep, 34.5 in (876 mm) high, and takes a 1.5 in top. The heights land within 14 mm of each other. The widths do not, and the widths are the ones that repeat.

Five units in a row lose 48 mm (1 7/8 in) when the substitution is made, which is roughly one filler panel, and the run fails at the first appliance rather than gradually. The arithmetic is set out in millimetre cabinet and joinery sizes, and the carcass, door and worktop comparison is in kitchen cabinet sizes, US inches against European millimetres. Appliance apertures follow the same split, with a 600 mm and a 24 in family that look interchangeable in a catalogue and are not, as appliance sizes by country sets out.

Doors and windows: the heights that never line up#

Door leaf sizes are the most quietly incompatible items in a house. The US uses 80 in (2032 mm) heights, the UK 1981 mm, continental Europe 2000 mm, and Australia 2040 mm. The spread is 59 mm, which is far too small to notice in a photograph and far too large to swap a leaf into an existing frame.

Height is the part that reaches beyond the door itself. A room is set out from its door head: window heads, the top of panelling, picture rails and cabinet tops all take their line from it. Raise the head by 19 mm with an imported leaf and the alignment breaks everywhere at once, which is why imported joinery can fit perfectly and still look wrong. Leaf sizes, frames and thicknesses by market are in door sizes by country.

Windows split on a different axis. Sizes are modular in metric markets and nominal in the US, and the rules that actually bind are the escape ones: the US requires a 5.7 sq ft (0.53 m2) net clear opening for emergency escape, while England's guidance asks for 0.33 m2 with no dimension under 450 mm. Window sizes by country compares the two sets alongside sill height rules.

Bathrooms: the fittings that do not interchange at all#

Sanitaryware belongs in the third category, because plumbing connections fix it. A UK bath is 1700 x 700 mm (67 x 27.5 in) as standard. A US alcove bath is 60 x 30 in (1524 x 762 mm). The UK bath is 176 mm (7 in) too long for the US alcove and 62 mm too narrow, so there is no version of the swap that works. Toilets divide on the rough-in: the US fixes the waste centre 12 in (305 mm) from the finished wall, while UK and European pans connect to a 110 mm soil pipe with no equivalent convention. Basin and bath wastes run 32 to 40 mm in Europe against 1.25 to 1.5 in in the US. The comparison, fixture by fixture, is in bathroom fixture sizes by country.

What is legally different#

The English figures are a planning standard rather than a building regulation, so they bite only where a local authority has adopted them, which is the sort of distinction the standards and codes reference exists to keep straight. The heights and their knock-on effects on doors, trim and curtain drops are in ceiling heights and minimum room heights by country, and the floor areas alongside the workable figures we recommend are in standard and minimum room sizes and minimum room size standards by country.

Services, furniture and buying across a border#

Services are set by wiring rules rather than by ergonomics, so they vary more than anything else in a house. US receptacles sit 12 to 18 in (305 to 455 mm) above the floor by convention, while new UK homes must place sockets and switches within 450 to 1200 mm (18 to 47 in) under Approved Document M, a band chosen for reach rather than for tidiness. Socket and switch heights by country sets out each market and its bathroom zone rules.

Furniture is the last category, and it is the one where nothing is illegal and everything is slightly wrong. British and American upholstery are sized to different rooms, and the differences in length and depth are enough to change which walkways survive, as furniture sizes, UK against US explains.