826mm internal doors (2040 x 826mm metric)
826mm doors belong to the metric size family, normally 2040 x 826 x 40mm. They are fitted in newer UK housing and are the standard across Ireland. A metric door is taller, wider and thicker than the imperial size it looks closest to, so the two families cannot be swapped.
Metric doors are where a confident measurement goes wrong. Somebody measures a width of roughly 830mm, decides it is close enough to 838mm, orders the imperial door and finds it is 60mm too short in height.
Height is the giveaway, not width, and it takes one measurement to settle.
Showing all 3 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 sizes
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How to tell metric from imperial in under a minute
Measure the height of the opening. Imperial doors are 1981mm tall. Metric doors are 2040mm. That is a 59mm difference, which is far too much to trim and far too obvious to miss once you have the tape on it.
Thickness is the second tell. Imperial internal doors are usually 35mm, metric ones 40mm. A 40mm leaf in a lining rebated for 35mm will not sit right against the stop.
| Imperial family | Metric family | |
|---|---|---|
| Height | 1981mm (78") | 2040mm |
| Common widths | 610, 686, 762, 838mm | 526, 626, 726, 826, 926mm |
| Typical thickness | 35mm | 40mm |
| Usually found in | UK housing built before the 1990s | Newer UK housing, and standard across Ireland |
Why you cannot substitute one for the other
The height difference alone rules it out. You cannot add 59mm to a door, and taking 59mm off a metric door to fit an imperial opening removes far more than any manufacturer allows — on most doors it would cut straight through the bottom rail.
If you have a mixed house, which happens after an extension, buy each opening the door it needs and accept that the two will differ slightly in height. That reads far better than a door that has been butchered to fit.
The rest of the metric range
826mm is the most-fitted metric width, filling the role 762mm plays in the imperial family. The narrower sizes cover the same jobs 686mm and 610mm cover in an older house: bathrooms, box rooms and cupboards.
- 2040 x 526mm — cupboards and very narrow openings.
- 2040 x 626mm — box rooms, cloakrooms and store cupboards.
- 2040 x 726mm — bathrooms, en-suites and smaller bedrooms.
- 2040 x 826mm — the standard room door.
- 2040 x 926mm — wide openings and accessible routes.