Skirting Board Length Calculator
The perimeter is 2 × (length + width), less the door openings: a 4.2 × 3.4 m room is 15.2 m, and one 0.9 m door leaves 14.3 m. Add 10% for joints and mitre cuts to reach 15.7 m, then divide by a 2.4 m stock length for 6.55 — so you buy 7 lengths, rounded up because short ends are unusable.
Your numbers
Skirting needed
15.73m
Lengths to buy
7
Perimeter
15.2m
Formula
Skirting needed = (2 × (Length + Width) − Door opening width × Door openings) × (1 + Waste allowance ÷ 100), Lengths to buy = ⌈Skirting needed ÷ Stock length⌉
Mitred corners often mean one whole length per wall, which is more than the metres suggest. Where walls bow, a single uncut length across the long wall hides the gap better than two pieces joined in the middle.
What to enter
| Input | Default | Accepted range |
|---|---|---|
| Length (m)The measurement across, side to side. | 4.2 | 0 and up |
| Width (m)The measurement front to back. | 3.4 | 0 and up |
| Door opening width (m)The clear width of a door opening, measured at the frame rather than the door. | 0.9 | 0 and up |
| Door openingsHow many openings the room has; decide up front whether fitted units count too. | 1 | 0 ~ 10 |
| Stock length (m)The length of one length as sold; 2.4 m and 3.6 m are the usual sizes. | 2.4 | 0 and up |
| Waste allowance (%)The extra bought to cover breakage and offcuts. | 10 | 0 ~ 50 |
Step by step
Quick reference table
Results when only Length (m) changes and everything else stays put.
| Length (m) | Skirting needed (m) | Lengths to buy | Perimeter (m) |
|---|---|---|---|
| 2.1 | 11.11 | 5 | 11 |
| 3.15 | 13.42 | 6 | 13.1 |
| 4.2 | 15.73 | 7 | 15.2 |
| 6.3 | 20.35 | 9 | 19.4 |
| 8.4 | 24.97 | 11 | 23.6 |
What each result means
| Result | At default values |
|---|---|
| Skirting needed (m)The total metres of skirting needed, waste included. | 15.73 |
| Lengths to buyLengths to buy, rounded up, because short leftover ends are unusable. | 7 |
| Perimeter (m)The total length around the outside of a shape. | 15.2 |
Common mistakes
Mitred corners often mean one whole length per wall, which is more than the metres suggest. Where walls bow, a single uncut length across the long wall hides the gap better than two pieces joined in the middle.
Glossary
- Length
- The measurement across, side to side.
- Width
- The measurement front to back.
- Door opening width
- The clear width of a door opening, measured at the frame rather than the door.
- Door openings
- How many openings the room has; decide up front whether fitted units count too.
- Stock length
- The length of one length as sold; 2.4 m and 3.6 m are the usual sizes.
- Waste allowance
- The extra bought to cover breakage and offcuts.
- Skirting needed
- The total metres of skirting needed, waste included.
- Lengths to buy
- Lengths to buy, rounded up, because short leftover ends are unusable.
- Perimeter
- The total length around the outside of a shape.
Frequently asked questions
Q. How is Skirting Board Length Calculator calculated?
Skirting needed = (2 × (Length + Width) − Door opening width × Door openings) × (1 + Waste allowance ÷ 100), Lengths to buy = ⌈Skirting needed ÷ Stock length⌉ — The perimeter is 2 × (length + width), less the door openings: a 4.2 × 3.4 m room is 15.2 m, and one 0.9 m door leaves 14.3 m. Add 10% for joints and mitre cuts to reach 15.7 m, then divide by a 2.4 m stock length for 6.55 — so you buy 7 lengths, rounded up because short ends are unusable.
Q. Can you walk through an example?
With Length 4.2m, Width 3.4m, Door opening width 0.9m, Door openings 1, Stock length 2.4m, Waste allowance 10%, the answer is Skirting needed 15.73m.
Q. What do I need to enter?
Enter Length, Width, Door opening width, Door openings, Stock length, Waste allowance. The result recalculates as you type, and an empty box counts as zero.
Q. How much does the answer move if I change a number?
Changing only Length (m) moves the answer to Length (m) 2.1 → Skirting needed (m) 11.11 and Length (m) 8.4 → Skirting needed (m) 24.97. The table below lays out five steps.
Q. How are the numbers rounded?
Money is shown to the nearest whole unit, percentages to one decimal place and everything else to two. What you see is rounded; the calculation itself carries the unrounded value forward.
Q. Anything to watch out for?
Mitred corners often mean one whole length per wall, which is more than the metres suggest. Where walls bow, a single uncut length across the long wall hides the gap better than two pieces joined in the middle.
Related calculators
Keep your length units consistent across inputs — mixing centimetres and metres throws results far off.