How to use this calculator
- Enter the room size, or the total wall length for odd-shaped rooms.
- Enter the number and width of doorways.
- Choose the board length you'll buy.
The formula
Length = 2 × (length + width) − doorways
Boards = 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.
Sources
- Method: room perimeter minus doorways, plus extra for cuts.
Formulas last reviewed: September 29, 2026. How we check our formulas