Getting a door measurement right is essential for a perfect fit. It prevents draughts, sticking and unnecessary adjustments.
Whether you’re replacing an old door or fitting a new one into a fresh opening, this guide covers how to measure accurately in millimetres, understand clearances and gaps, and know when to consider a bespoke solution.
Where to Measure
When swapping out an existing door, always measure the frame, not the door itself, as changes in temperature and humidity can cause doors to swell or shrink.
If you’re starting without a frame, measure brick-to-brick across the top, middle and bottom for the width, and down the left, centre and right sides for the height.
Record the smallest of each measurement for precision. Accuracy here makes all the difference.
Mind the Gaps
A well-fitted door needs small, even gaps to open and close smoothly, around 3mm at the top and sides, and roughly 9mm along the bottom.
New doors usually come with a solid timber lipping, which allows for a little trimming or planing if necessary.
Always follow the manufacturer’s guidance on how much can be safely removed so you don’t compromise the door’s structure or finish.
UK Door Sizes and Custom Options
Standard UK door sizes are widely used, with 1981 × 762 × 35 mm (6’6” × 2’6”) being the most common. Other typical internal sizes include:
- 1981 × 686 × 35 mm (6’6” × 2’3”)
- 1981 × 838 × 35 mm (6’6” × 2’9”)
Fire doors (FD30) are thicker at 44 mm to meet safety standards. For unusually sized openings or older properties with uneven frames, a bespoke door will guarantee the ideal fit.
All you’ll need is a metal tape measure, a pencil and something to note your results. Clear away any obstacles, trims or old stops before you start.
Measure in millimetres for full precision, recording the smallest values for each dimension.
Don’t forget to include the frame depth and the rebate, where the door will sit, to ensure your new door fits securely and neatly.
If measuring feels a little daunting, leave it to the professionals at Mid Wales… We’ll handle every detail to ensure your new door fits flawlessly, as part of our complete service.
LOOKING FOR A NEW REPLACEMENT DOOR?
From French and patio to bi-folding, we offer an incredible variety of doors inlcuding the latest front and back door designs, all of which are made to measure for the perfect fit to your home.
LOOKING FOR A NEW REPLACEMENT DOOR?
From French and patio to bi-folding, we offer an incredible variety of doors inlcuding the latest front and back door designs, all of which are made to measure for the perfect fit to your home.
REQUEST YOUR FREE QUOTE
Simply fill in your details for your free, no obligation quotation, and click "Get Quote"