When purchasing new doors customers are often surprised to find that doors come in quite a range of sizes. It is important when purchasing doors that you measure every door in your house as quite often there will be different size doors required even if all your doors look the same size. 

If you don't have a tradesman measuring for you the easiest thing to do is measure your existing doors if they fit reasonably well. If you can’t measure the existing doors or they don't fit well, you will need to measure the opening of the door frame. You need the height, width and thickness.

Take three measurements at the top, middle and bottom in width
- See diagram Arrow's A

Take two measurements of the height at 2 different points
- See diagram Arrow's B

Use the larger of both sets of measurements as the size you require for the height and width.

Finally measure the thickness of the existing door or depth of the rebate - See diagram Arrow C

Choose carefully the closest match to your measurements in sizes available for the door you've chosen.
Remember doors can be trimmed down usually by 6mm - 32mm overall in width and height. Check the door's specification on the product's page to see how much it can be trimmed down.

The chart below shows a full range of door sizes that are produced by manufacturers. Its shows the measurements in metric and imperial (millimetres, feet and inches or just inches).
Please note not all sizes will be available in every door style. Generally, the more popular doors or doors that have been produced for a long time will have a larger range of available sizes.
Please see the "Available Sizes" drop down menu on the product page for available sizes of the door you are thinking of purchasing.
The most popular sizes in the UK ar highlighted in orange.