Walls
Enter different wall lengths, then choose the paint and tin size.
- Litres = net wall area × coats ÷ coverage, then add the chosen allowance. Tin counts round up; primer and finish coats need separate plans.
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Paint Calculator
Plan wall, ceiling and fence paint with measured areas, coats, product coverage and whole tins.
What does a worked calculation look like?
Two walls of 5 × 2.5 m and two of 4 × 2.5 m give 45 m². Subtracting 4.7 m² of doors and windows leaves 40.3 m². Two coats at 10 m² per litre need 8.06 L, or 8.866 L with a 10% allowance, so four 2.5 L tins (10 L) are needed and about 1.1 L is left.
Method and practical checks
- Litres = net wall area × coats ÷ coverage, then add the chosen allowance. Tin counts round up; primer and finish coats need separate plans.
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Every calculation option
Ceiling
Add the ceiling sections that use the same paint.
- Flat ceiling area is the sum of non-overlapping rectangles. Sloped ceilings need measured surface dimensions.
Fence
Use the painted face dimensions and count one or both sides.
- Fence calculation uses full face area; slats and gaps alter real use. Enter the product coverage for the actual surface and finish.
Worked example
Two walls of 5 × 2.5 m and two of 4 × 2.5 m give 45 m². Subtracting 4.7 m² of doors and windows leaves 40.3 m². Two coats at 10 m² per litre need 8.06 L, or 8.866 L with a 10% allowance, so four 2.5 L tins (10 L) are needed and about 1.1 L is left.
| Input | Value |
|---|---|
| Walls | Length 5 m, Height 2.5 m, Number of walls 2 · Length 4 m, Height 2.5 m, Number of walls 2 |
| Total measured openings | 4.7 m² |
| Coats | 2 |
| Coverage per coat | 10 m²/L |
| Extra allowance | 10 % |
| Pack size | 2.5 L |
| Result | Value |
|---|---|
| Paintable area | 40.3 m² |
| Paint before allowance | 8.06 L |
| Required quantity | 8.866 L |
| Packs to buy | 4 |
| Purchase quantity | 10 L |
| Left over | 1.134 L |
Reading the result
- The coverage figure on the tin is the biggest source of error. Use the value for your product and surface; rough plaster or a strong colour change can need more paint or an extra coat.
- Primer or mist coats are a different product with a different coverage, so plan them separately.
- A little leftover paint is useful for touch-ups; if the result is only just above a tin boundary, check whether a smaller tin is available instead.
Should I enter floor area or wall area?
For walls, measure each wall's length and height and subtract the openings you choose to exclude. A 5 × 4 m room with 2.5 m walls has 45 m² of wall before openings. The floor's 20 m² is not the wall area.
Does the tin's coverage include two coats?
Use the coverage for one coat unless the product instructions explicitly state otherwise. Two coats over 40.3 m² at 10 m² per litre need 8.06 L before allowance. Primer, ceilings and woodwork use their own products and should be calculated separately.
How does the worked paint estimate become a purchase?
A calculated 3.2 L requirement needs two 2 L tins when those are the available packs. The purchase is 4 L, while the theoretical requirement remains 3.2 L. Use the actual product coverage, required coats and measured wall area; add an explicit allowance before rounding to whole tins.
Calculation/content reviewed 4 October 2026. Source: Babushka Market’s displayed formulas, units and labelled editable assumptions. How the estimates work