Coving calculator: how to measure, lengths and cuts
The calculator needs JavaScript. The worked example, formula and figures below show exactly how it works, so you can do the sum yourself. A guide, not advice. Check your supplier's or maker's figures before ordering.
Short answer
Worked example
| You enter | Value |
|---|---|
| Walls | Wall 1: wall length 4 m; Wall 2: wall length 3.5 m; Wall 3: wall length 4 m; Wall 4: wall length 3.5 m |
| Length of coving you can buy | 3 m |
| Waste allowance | 10% |
| Mitre allowance per piece | 100 mm |
| Internal corners | 4 |
| External corners | 0 |
Order: 6 × 3 m lengths of coving
| Result | Value |
|---|---|
| Lengths to buy | 6 |
| Perimeter | 15 m |
| Coving bought | 18 m |
| Internal mitres | 4 |
| External mitres | 0 |
| Mitre cuts (two per corner) | 8 |
| Joins on long walls | 4 |
Mitre angle guide
- Square corners (90°): cut each piece at 45°
| Length | Cut into | Offcut |
|---|---|---|
| 1 (3 m) | Wall 1 (part 1 of 2): 3 m | 0 m |
| 2 (3 m) | Wall 2 (part 1 of 2): 3 m | 0 m |
| 3 (3 m) | Wall 3 (part 1 of 2): 3 m | 0 m |
| 4 (3 m) | Wall 4 (part 1 of 2): 3 m | 0 m |
| 5 (3 m) | Wall 1 (part 2 of 2): 1.2 m; Wall 3 (part 2 of 2): 1.2 m | 0.6 m |
| 6 (3 m) | Wall 2 (part 2 of 2): 0.7 m; Wall 4 (part 2 of 2): 0.7 m | 1.6 m |
Show the working
- Perimeter: 4 + 3.5 + 4 + 3.5 = 15 m
- By waste: 15 m × 1.1 (10% waste) ÷ 3 m, rounded up = 6 lengths
- By cut list: pieces with 100 mm allowance each, packed into 3 m lengths = 6 lengths
- Lengths to buy: the larger of 6 and 6 = 6
- Mitres: 4 internal + 0 external corners; 8 cuts
How it works
- Perimeter = the sum of the wall lengths
- By waste: lengths = perimeter × (1 + waste) ÷ stock length, rounded up
- By cut list: each wall is cut from full lengths plus one shorter piece (plus the mitre allowance), packed longest first (first-fit decreasing)
- Lengths to buy = the larger of the two
- Mitres: one per corner, each made from two cuts; a square corner is cut at 45°, any other corner at half its angle
- Adhesive tubes = perimeter ÷ metres per tube, rounded up
Coving is cut in a mitre box held upside down, as if the box were the ceiling and wall: follow the coving maker's template.
Join long walls away from the room's focal point, and stagger joins so they're less visible.
Our default (adjustable)
These are typical planning figures and our own allowances, not facts about your product. Change any of them in the calculator to match your bag, pack or tin.
| Figure | Our default (adjustable) | Kind | Source |
|---|---|---|---|
| Waste allowance | 10 % | Our assumption Not yet checked against the source | Our choice: change it to suit your job brief v2 PL4 (test CV1 uses 10%). |
| Mitre allowance per piece | 0.1 m | Our assumption Not yet checked against the source | Our choice: change it to suit your job Allowance per piece for squaring ends and mitres (brief v2 FL2). |