The UK’s most common internal door size is 762mm wide by 1981mm high — the 2ft 6in by 6ft 6in imperial legacy
The question of what constitutes a “standard” door size in the UK is more nuanced than a single number. The vast majority of internal doors in British homes are 762mm wide and 1981mm high, a direct carry-over from the imperial measurement of 2 feet 6 inches by 6 feet 6 inches.
The most common standard door size in the UK is 762mm wide by 1981mm high, accounting for about 70% of internal doors. For new builds, 838mm width is increasingly standard to meet accessibility rules.
- Most UK internal doors are 762mm wide by 1981mm high.
- The 762mm x 1981mm size accounts for about 70% of internal door stock.
- BS 4787-1:1980 lists standard widths of 686mm, 762mm, 838mm, and 915mm.
- New-build homes since 2004 require a minimum 775mm clear opening width.
- Measure the door leaf in three places, taking the smallest measurement.
- The UK's most common internal door size is 762mm wide by 1981mm high — the 2ft 6in by 6ft 6in imperial legacy
- How to measure your existing door frame correctly to avoid ordering the wrong size
- Quick numbers — standard UK door sizes in millimetres and imperial
- The direct answer the standard UK door size is 762mm x 1981mm for internal doors, but you must check your frame before buying
- How to verify your installer and ensure compliance with UK building regulations
- When you need a non-standard door size and what that costs in 2026
- How building regulations Part M affects door widths in new homes and renovations
Industry supply-chain data cited by the Door and Hardware Federation indicates that this size accounts for approximately 70% of the UK’s internal door stock (Door and Hardware Federation, 2026). This dominance is a legacy of pre-2000 construction, when most homes were built using imperial dimensions, and replacement doors must match existing frames.
British Standard BS 4787-1:1980, which remains current in 2026, lists 762mm, 838mm, 915mm, and 686mm as standard widths, all with a default height of 1981mm. However, since 2004, new-build homes must comply with Part M of the Building Regulations, which recommends a minimum clear opening width of 775mm for accessibility. To achieve this, the door leaf must be at least 838mm wide, making that size increasingly common in modern properties.
How to measure your existing door frame correctly to avoid ordering the wrong size
The single most common mistake is measuring the frame opening rather than the door leaf itself. To get the correct size for a replacement door, measure the door leaf in three places: across the top, middle, and bottom for width, and along the left, centre, and right for height. Always take the smallest measurement from each set (Which? home improvement guides, 2026).
Standard door thickness in the UK is 35mm for internal doors and 44mm for external doors — confirm this before ordering hinges or locks. If you are replacing the entire door and frame, measure the structural opening (brick-to-brick or stud-to-stud), which will be larger than the door leaf.
Common pitfalls include measuring with architrave still attached, or assuming the existing door is a standard size when it may have been cut down or the frame may have settled over decades. The Door and Hardware Federation’s installation best-practice guidance stresses that no measurement should be taken for granted.
Quick numbers — standard UK door sizes in millimetres and imperial
| Door type | Nominal width (mm) | Nominal width (imperial) | Nominal height (mm) | Nominal height (imperial) | Typical use |
|---|---|---|---|---|---|
| Internal | 686 | 2’3″ | 1981 | 6’6″ | Cupboards, small rooms (pre-2000 homes) |
| Internal | 762 | 2’6″ | 1981 | 6’6″ | Standard bedrooms, living rooms (most UK homes) |
| Internal | 838 | 2’9″ | 1981 | 6’6″ | Part M compliant new-builds, wider access |
| Internal | 915 | 3’0″ | 1981 | 6’6″ | Double-width openings, wheelchair access |
| External (front/back) | 762 | 2’6″ | 1981 | 6’6″ | Older homes, side entrances |
| External (front/back) | 838 | 2’9″ | 1981 | 6’6″ | Standard new-build front doors |
| External (modern) | 915 | 3’0″ | 2032 | 6’8″ | Contemporary homes, taller entrance |
| French/Patio (pair) | 1219 | 4’0″ | 1981 | 6’6″ | Single-width pair |
| French/Patio (pair) | 1524 | 5’0″ | 1981 | 6’6″ | Wider pair |
| French/Patio (pair) | 1829 | 6’0″ | 1981 | 6’6″ | Full-width pair |
Sources: BS 4787-1:1980, NHBC Standards Chapter 6.9, and industry catalogues from LPD, Door Superstore, and Magnet Trade.
The direct answer the standard UK door size is 762mm x 1981mm for internal doors, but you must check your frame before buying
If you need a quick answer for a typical UK home built between 1930 and 2000, the standard internal door size is 762mm wide by 1981mm high. This single size fits the vast majority of such properties, but it is not guaranteed for any individual house.
The “standard” is a direct legacy of imperial building practice — 2ft 6in wide, 6ft 6in high — and has been carried into metric building regulations as a nominal dimension. If your frame is older or non-standard (Victorian, 1960s system-built, or a modern Part M compliant property), you will likely need an 838mm wide or 686mm wide door instead.
The Royal Institute of British Architects (RIBA) Plan of Work stage guidance and Building Regulations Approved Document M both stress that you should never assume “standard” means “universal” — always measure before ordering, especially if the property was built before 1900 or after 2010.
How to verify your installer and ensure compliance with UK building regulations
For a like-for-like internal door replacement, no formal certification is required. However, any work that alters the structural opening must comply with Part B (fire safety) and Part M (accessibility) of the Building Regulations (GOV.UK, 2026).
For external doors, the installer must be registered with FENSA, CERTASS, or a similar competent person scheme if the work involves glazing or replacement of the whole frame. This allows self-certification without a separate Building Control inspection. Gas Safe Register applies only to doors containing gas appliances (e.g., boiler cupboard doors), not to standard external doors. MCS certification is not relevant for doors; it covers renewable energy systems only.
TrustMark is not mandatory but indicates that the installer follows industry standards and has been vetted. Checking TrustMark can give you confidence that the work will meet building regulations requirements.
When you need a non-standard door size and what that costs in 2026
Non-standard sizes — such as 711mm, 864mm, or 940mm wide, or heights above 2032mm — typically add 30–60% to the door price compared to standard 762mm x 1981mm sizes. A standard internal door costs £40–£80 at retail (B&Q, Wickes, Screwfix); a non-standard size in the same material costs £100–£200 from specialist suppliers like Door Superstore, LPD, or local joiners.
Custom-made doors from a joinery shop cost £200–£600 depending on material (solid oak, engineered, MDF) and finish, with a lead time of 4–8 weeks. If your frame is non-standard, you may save money by adjusting the frame to accept a standard door rather than ordering a custom door leaf — a joiner can pack or plane a frame for £50–£150 (Checkatrade cost guide, 2026).
How to measure a door frame for replacement
How building regulations Part M affects door widths in new homes and renovations
Part M of the Building Regulations (2010 edition, 2013 amendments, still current in 2026) requires a minimum clear opening width of 775mm for the main entrance door and 750mm for internal doors in new dwellings. “Clear opening width” means the unobstructed gap when the door is open at 90 degrees — the door leaf must be at least 838mm wide to achieve 775mm clearance after accounting for the frame and hinges.
For renovations, Part M does not apply retrospectively unless you are making a material change of use or substantially rebuilding the property. However, if you are replacing doors in a ground-floor bathroom or WC and the work requires Building Control approval, you must consider Part M. The Equality Act 2010 applies to non-domestic premises and common areas of flats, requiring accessible door widths of 800mm clear opening minimum (GOV.UK planning portal guidance, 2026).
Building regulations for door replacement in UK homes
Frequently Asked Questions
The most common standard internal door size is 762mm wide by 1981mm high, based on the imperial 2ft 6in by 6ft 6in. According to the Door and Hardware Federation, this size covers about 70% of UK internal doors.
Standard widths under British Standard BS 4787-1:1980 include 686mm, 762mm, 838mm, and 915mm. The 762mm width is the most common, but 838mm is increasingly used in new builds to meet Part M of the Building Regulations.
The standard height for UK internal doors is 1981mm (6ft 6in). This applies to most standard widths listed in BS 4787-1:1980, which remains current in 2026.
Standard internal door thickness in the UK is 35mm. External doors are typically 44mm thick. Always confirm thickness before ordering hinges or locks.
Measure the door leaf in three places: top, middle, and bottom for width, and left, centre, and right for height. Take the smallest measurement from each set, as recommended by Which? home improvement guides. Do not include architrave in your measurements.
