12th Dec 2022 -

Fitting an incorrectly sized door within a building project can cause massive issues, either being too large for the frame or small enough to cause draughts. There are rarely standardised measurements for doors, though as we’ll explain in this guide, within the UK there is a selection of common door sizes for sale.

What Is the Standard Internal Door Size in the UK?

When it comes to internal doors, you won’t find a standardised series of measurements as you would in other elements of a building. If you’re looking to replace an internal door within a house or to source internal doors for a building, the size you need will usually be within a standard range. 

Perhaps the most popular door measurements are 1981mm x 762mm x 35mm, which will be 2’6 in width and 6’6 in height. However, through our site, you’ll find a varying range of sizes for standard internal doors, shown below.

Metric and Imperial Door Size Conversion Chart

To give an indication of the different sizes available on standard doors, we’re going to show the sizes of just one of the door designs we stock, the XL Joinery Internal Oak Palermo, in both imperial and metric door sizes.

Door Size (Metric)Door Size (Imperial)
1981mm x 457mm x 35mm 78in x 18in x 1.38in
1981mm x 533mm x 35mm78in x 21in x 1.38in
1981mm x 610mm x 35mm78in x 24in x 1.38in
1981mm x 686mm x 35mm78in x 27in x 1.38in
1981mm x 711mm x 35mm78in x 28in x 1.38in
1981mm x 762mm x 35mm78in x 30in x 1.38in
1981mm x 838mm x 35mm78in x 33in x 1.38in
2032mm x 813mm x 35mm80in x 32in x 1.38in
2040mm x 526mm x 40mm80.3in x 20.7in x 1.57in
2040mm x 626mm x 40mm80.3in x 24.6in x 1.57in
2040mm x 726mm x 40mm80.3in x 28.5in x 1.57in
2040mm x 826mm x 40mm80.3in x 32.5in x 1.57in
2040mm x 926mm x 40mm80.3in x 36.5in x 1.57in

Standard Door Width

At the table above shows, it’s difficult to talk about a standard width when it comes to internal doors. However, if judging based on the most common 1981mm x 762mm sizing, then the standard door width is 762mm, or 30 inches (2’6).

Standard Door Height

There is less variation when it comes to the heights of internal doors, but again when talking about standards we are referring to popularity rather than any building regulations. 1981mm is the standard height for popular door models, rising to 2040mm in some designs.

Fire Door Sizes

Fire doors are typically manufactured in all standard door sizes available in the UK, however, they will typically be thicker, at least 45mm. Fire doors will be marked as FD30 or FD60, indicating 30 or 60 minutes of fire resistance.

Internal Door Frame Sizes

Much like the doors themselves, door frame sizes will vary. You’ll be looking to buy a door frame that is slightly larger than your door to get a perfect fit, with an extra 2 inches in width and 2.5 inches in height recommended. Many door frames are built to be adjustable, meaning that they can be neatly installed around a range of door sizes.

Bedroom with French Door Balcony

What is the Standard External Door Size?

Much like internal doors, external doors, such as back doors, have no strict standardised sizes. 1981mm x 762mm remains popular, but wider options (Over 812mm) are needed to make a building more navigable for wheelchair users. While heights will remain mostly consistent, far wider sliding doors and French external doors will also be available.

The Standard Front Door Size in the UK

Again, there is no standard size when looking to buy front doors, though 1981mm x 762mm will remain a standard option, with larger widths and heights available.

Internal and External Doors Delivered across the UK

Building Materials Nationwide offers a selection of doors and door fixings for sale, with quality internal and external doors supplied in a wide range of sizes. We aim to be the only destination a professional needs for all of their supplies, saving them time and money through our trade accounts. Trade account holders get access to a dedicated account manager, who they can contact via phone or email. Account managers will source you the products you need, whether they are on our website or not, delivering them to you at a fantastic trade price. Sign up for a trade account today.

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