Guide
Standard internal door sizes in the UK
The most common UK internal door is 1981mm by 762mm, or 6ft 6in by 2ft 6in, and 35mm thick. Metric doors are 2040mm tall, usually 726mm or 826mm wide, and fire doors are 44mm thick.
The imperial sizes
Most British homes still use doors made to imperial sizes, all 1981mm (6ft 6in) tall. The width is what varies.
| Size (height by width) | Imperial | Where it is used |
|---|---|---|
| 1981mm by 457mm | 6ft 6in by 1ft 6in | Narrow cupboards |
| 1981mm by 533mm | 6ft 6in by 1ft 9in | Cupboards and airing cupboards |
| 1981mm by 610mm | 6ft 6in by 2ft | Larger cupboards, small en suites |
| 1981mm by 686mm | 6ft 6in by 2ft 3in | Bathrooms and box rooms |
| 1981mm by 711mm | 6ft 6in by 2ft 4in | Bathrooms and bedrooms in older houses |
| 1981mm by 762mm | 6ft 6in by 2ft 6in | The usual bedroom and living room door |
| 1981mm by 838mm | 6ft 6in by 2ft 9in | Wider openings and better access |
If you are replacing one door in a house and do not know the size, 762mm is the most likely answer, but measure the opening before ordering anything.
The metric sizes
Metric doors are 2040mm tall and come in widths of 526mm, 626mm, 726mm, 826mm and 926mm. They are common in some new builds and in houses with metric door linings. A metric door will not fit an imperial lining, or the reverse, without the lining being changed or the door trimmed, and 59mm of height is beyond any door's trimming allowance.
Thickness
Standard internal doors are 35mm thick, whether hollow-core, semi-solid or solid. Some solid timber doors are 40mm. Fire doors are thicker: an FD30 door, the common half-hour rating, is usually 44mm, and an FD60 door is usually 54mm. External doors are 44mm. The thickness matters because the lining's door stop and the hinges are set for it, so a 44mm fire door going into a lining made for a 35mm door means moving the stops.
How to measure for a new door
Measure the opening, not the old door. Old doors have often been trimmed, planed or have shrunk.
- Measure the width between the inside faces of the lining at the top, the middle and the bottom. Take the smallest figure.
- Measure the height on both sides from the floor to the underside of the head. Take the smallest figure, and note what floor covering is going down.
- Measure the two diagonals of the opening. If they differ by more than a few millimetres, the lining is out of square and the door will need shaping to fit it.
- Note which side the hinges are on and which way the door opens.
A door is fitted with a small even gap all round, about 2mm to 3mm at the sides and top, so a 766mm opening takes a 762mm door. The gap at the bottom depends on the floor covering, and it is worth deciding the flooring before the doors are hung. A door trimmed for carpet that then meets a thick engineered board has to come off again.
When the opening is not a standard size
Older houses often have openings that match nothing in a catalogue. There are three ways round it. A slightly larger door can be trimmed, but hollow-core doors only have a narrow solid lipping round the edge, and the manufacturer's trimming allowance is the limit. A made-to-measure door costs more but fits the opening as it is. Or the lining is replaced and set to a standard size, which suits a renovation where the walls are being made good anyway.
Width also affects access. The clear opening is less than the door width because of the door stop and the thickness of the open door itself, so a 686mm door leaves a narrow gap. A 762mm or 838mm door makes moving furniture, pushchairs and wheelchairs easier, and is worth considering when a lining is being replaced.
Fire doors are a different job
Some doors in some homes have to be fire doors: on the escape route in a house with a storey more than 4.5m above the ground, which usually means after a loft conversion on a two-storey house, and between a house and an integral garage. A fire door can only be trimmed within its certified limits, and it must be hung with the right hinges, strips and gaps, so it is not a straight swap for a standard door.
What door fitting costs
Hanging an internal door on an existing lining typically costs £80 to £180, including hinges and a latch. Supplying and fitting a standard door is usually £150 to £350, a new lining and architrave adds £60 to £120 per opening, and a certified fire door installation is around £250 to £450. A carpenter hanging a whole house of doors will usually price it as a job rather than door by door.
Common questions
What is the standard bedroom door width in the UK?
762mm, or 2ft 6in, at 1981mm tall. Metric equivalents are 726mm or 826mm wide at 2040mm tall.
How much gap should there be under an internal door?
Enough to clear the finished floor covering, commonly around 10mm. Where a room relies on air passing under the door for ventilation, the gap may need to be larger, so check before trimming.
Can I cut a door down to fit?
A little, within the manufacturer's allowance. Take equal amounts from each side where possible so the door stays balanced, and seal any cut edge before hanging it.
Why is my new door 2040mm tall when my old one was 1981mm?
You have bought a metric door for an imperial opening. Return it if you can; trimming 59mm off the height goes well beyond what most doors allow.