Getting door measurements right is crucial if you want to avoid draughts, sticking, or poor alignment.
This simple guide walks you through measuring in millimetres for both existing frames and new door sets, with expert advice on allowances, clearances, and when a bespoke door might be the best solution.
Measure the Frame or Opening
When replacing a front door, always measure the frame rather than the door itself, as doors can warp, swell or shrink over time.
If there’s no frame, measure the brick-to-brick opening with a metal tape measure, then deduct the frame size.
Take three width measurements (top, middle, bottom) and three height measurements (left, centre, right), noting down the smallest figures for accuracy.
Gaps, Clearances and Trimming
To ensure smooth operation, leave even gaps of around 3mm at the top and sides, and about 9mm at the bottom.
Most new doors have a lipping (a solid timber edge) that allows for slight trimming or planing, but always check the manufacturer’s guidelines for limits.
Getting this right ensures your new door opens and closes effortlessly, without catching or sticking.
UK Door Sizes and Bespoke Options
Most manufacturers use standard door sizes, 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-rated doors (FD30) are thicker at 44 mm, compared to the 35 mm of standard doors. If your opening doesn’t suit a standard size or shape, a bespoke door will ensure a perfect fit.
You’ll just need a rigid metal tape measure, pencil, and paper. Clear any obstructions and remove trims or door stops before you start.
Measure in millimetres and always record the smallest numbers for width, height, and depth.
Finally, don’t forget the frame depth and the rebate (where the door sits in the frame) to guarantee perfect alignment.
Not confident taking measurements yourself? Leave it to Amber’s experienced team. We’ll handle everything to make sure your new door fits perfectly – it’s included in our 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.
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