Skirting Board Calculator
Last updated: 12 August 2026
Work out how many lengths of skirting board you need for a room. Deducts doorways, adds a wastage allowance for mitre cuts, and tells you how many standard lengths to buy.
How the calculation works
Perimeter = 2 × (length + width). We subtract the width of each doorway, add a wastage allowance for mitre cuts at corners, then divide by the length skirting is sold in and round up.
Mitre wastage matters more than people expect: every external corner needs two 45° cuts, and an offcut shorter than the next run is scrap. Rooms with bay windows or alcoves need 15%.
Common skirting heights
| Height | Suits |
|---|---|
| 95–120mm | Modern homes, low ceilings |
| 145–170mm | Standard UK choice, most rooms |
| 195–220mm | Period properties, high ceilings |
| 250mm+ | Victorian and Georgian restoration |
A rule of thumb: skirting height of roughly 1/18th of the ceiling height looks proportionate. Taller skirting on low ceilings makes a room feel smaller.
Fitting tips
Scribe internal corners rather than mitring them — timber shrinks and mitred internals open up, while a scribed joint stays tight. Mitre external corners at 45°. Fix with grab adhesive plus a few pins, and always check for cables and pipes before nailing into a stud wall.
Frequently asked questions
How much skirting board do I need?
Measure the room perimeter, subtract the doorways, then add 10% for mitre cuts. A 4m x 3m room with one 0.9m door needs about 13.5 metres, which is four 4.2m lengths.
What length does skirting board come in?
4.2 metres is the most common UK length, with 3m, 2.4m and 5.4m also widely available. Longer lengths mean fewer joints on long walls, which looks noticeably better.
How much wastage should I allow for skirting?
10% for a standard rectangular room. Increase to 15% where there are bay windows, alcoves or lots of external corners, since each mitre generates an offcut that often cannot be reused.
What height skirting board should I choose?
145 to 170mm suits most UK homes. Period properties with high ceilings carry 195mm and above. A useful guide is roughly 1/18th of the ceiling height.
Should I mitre or scribe internal corners?
Scribe internal corners. Timber shrinks over time and mitred internal joints open into a visible gap, whereas a scribed joint stays tight. Use 45 degree mitres only on external corners.
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Estimates are for guidance only. Material dimensions, densities and coverage vary by supplier — always confirm quantities before ordering, and consult a qualified professional for structural work.