762mm internal doors (78" x 30")
762mm is the standard internal door width in the UK, written in the trade as 78" x 30" and measuring 1981 x 762 x 35mm. If a British house has one door size fitted more often than any other, it is this one, which is why it is the size most likely to be in stock and cheapest to replace.
The reason 762mm dominates is historic rather than designed. British doors were made to imperial sizes long before metrication, 30 inches was the sensible width for a room door, and the industry simply carried on making the same thing and printing the measurement in millimetres.
That history is why the trade still quotes doors in inches while selling them in millimetres, and why a "78 by 30" and a "1981 x 762" are the same door.
Showing all 5 doors
Prices are guide prices including VAT, taken from the smallest size and plainest finish of each door. They are not an offer to sell — confirm the price for your size and finish before ordering.
White Flush Internal Door
A plain flat door with nothing to catch dust or argue with the architecture — the honest choice for a modern house, a utility room, or anywhere the door is not the point.
- Primed MDF
- 35mm
Guide price from£38.40inc VAT11 sizesWhite Primed Shaker Door
Clean two-panel shaker lines in a white primed finish — the most forgiving door in a mixed-age house, and the cheapest way to make a landing look deliberate.
- Primed MDF
- 35mm
Guide price from£50.40inc VAT11 sizesOak 4-Panel Internal Door
A traditional four-panel oak door with raised mouldings — the default choice for Victorian and Edwardian houses, and the one most people picture when they say "oak door".
- Engineered oak
- 35mm
Guide price from£106.80inc VAT11 sizesOak Glazed 3-Light Door
Three glazed lights in an oak frame — for borrowing daylight from a hallway into a room that has none of its own.
- Engineered oak
- 35mm
Guide price from£150inc VAT7 sizesOak Cottage Ledged Door
Vertical boards with ledges across the back — a genuine cottage door for period properties, where a moulded panel door would look wrong.
- Solid oak
- 35mm
Guide price from£198inc VAT4 sizes
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How to measure your opening
Measure the opening, not the door that is currently in it. The existing door may have been trimmed to fit, may be the wrong size already, or may be hung in a frame that has moved.
- Measure the width inside the frame at the top, the middle and the bottom. Old openings are rarely square.
- Measure the height on both sides, from the floor covering you will actually have, not from bare boards.
- Work from the smallest width and the smallest height you measured.
- Allow for the gap around the leaf and for the floor covering under it.
- Compare that against the door size, and check the trimming allowance before assuming a slightly large door will do.
How much can you trim?
Every door has a maximum trimming allowance set by its manufacturer, and it is usually a few millimetres per edge on a standard internal door. Exceeding it can cut into the internal frame of the leaf and will generally void the guarantee.
The allowance differs by construction. A solid core door tolerates more than a hollow core one, where the stiles are narrow and there is very little material to lose. Take the figure from the instructions supplied with the door you have bought rather than from a rule of thumb.
Trim evenly. Taking 12mm off one edge and nothing off the other puts the panels or the glazing off centre, and on a panelled door that is immediately visible.
When 762mm is not the answer
If your opening measures around 826mm and the door height is closer to 2040mm than 1981mm, you have a metric opening and a 762mm door will not fill it. If the opening is a bathroom in an older house it is more likely to be 686mm. Measure first; the assumption is right most of the time, which is exactly why the exceptions catch people out.