How to use this calculator
- 1Enter the room size, or the total wall length for odd-shaped rooms.
- 2Enter the number and width of doorways.
- 3Choose the board length you'll buy.
- 4Tick the architrave box to count the door sets as well — one set per door side.
The formula
- 01Length = 2 × (length + width) − doorways
- 02Boards = length × (1 + extra %) ÷ board length, rounded up
Every inside and outside corner is cut at an angle, and short offcuts are rarely usable, so allow about 10 % extra.
Worked example
A 4 m × 3 m room with one 800 mm doorway needs 13.2 m of skirting.
With 10% extra and 2.4 m boards, buy 7 boards.
Tips before you buy
- Longer boards mean fewer joins on long walls.
- Buy the same profile for the whole house — profiles vary between shops.
Frequently asked questions
How much extra skirting should I buy?
About 10 % for mitres and offcuts. Rooms with many corners or bay windows may need more.
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Sources
- Method: room perimeter minus doorways, plus extra for cuts.
- Architrave: sold in sets of two legs and a head for one side of a door (UK legs about 2.1 m, head about 1 m); leg = door height + architrave width, head = door width + two architrave widths.
Formulas last reviewed: September 30, 2026 ·How we check our formulas