How to Measure for Internal Doors: Step by Step Guide
Measuring for internal doors correctly is essential to ensure a perfect fit. Whether you're replacing an existing door or fitting a new one, this comprehensive guide will walk you through the process step by step.
What You'll Need
- Tape measure (at least 3m)
- Pen and paper
- Spirit level (optional but recommended)
Step 1: Measure the Door Width
Measure the width of your existing door (not the frame) at three points:
- Top of the door
- Middle of the door
- Bottom of the door
Use the smallest measurement to ensure your new door will fit. Standard UK internal door widths are 610mm, 686mm, 762mm, and 838mm.
Step 2: Measure the Door Height
Measure the height of your existing door from top to bottom on both sides:
- Left side
- Right side
Use the smallest measurement. Standard UK internal door heights are 1981mm (6ft 6in) and 2040mm (6ft 8in).
Step 3: Measure the Door Thickness
Measure the thickness of your existing door. Standard internal door thicknesses are:
- 35mm - Standard internal doors
- 40mm - Some premium doors
- 44mm - Fire doors (FD30)
Step 4: Check the Frame (Door Lining)
If you're also replacing the frame, measure:
- Structural opening width - wall to wall
- Structural opening height - floor to top of opening
- Wall thickness - to determine lining depth
Standard UK Internal Door Sizes
| Imperial | Metric (mm) |
|---|---|
| 2ft 0in x 6ft 6in | 610 x 1981 |
| 2ft 3in x 6ft 6in | 686 x 1981 |
| 2ft 6in x 6ft 6in | 762 x 1981 |
| 2ft 9in x 6ft 6in | 838 x 1981 |
Top Tips for Measuring Internal Doors
- Always measure twice - double-check all measurements before ordering
- Account for clearance - you'll need 2-3mm gap on each side and top
- Check for square - use a spirit level to check if your frame is square
- Consider flooring - if you're fitting new flooring, account for the additional height
- Measure existing hinges - note the position for easier fitting
Need Help?
If you're unsure about any measurements, our team of door experts is here to help. Contact us or call +44 1282 270214 for advice.