Paint Calculator
Work out how much paint any area needs — from the area, the number of coats, and your paint's own coverage. No two paints cover the same, so coverage is yours to enter.
Paint is sold by the tin, but needed by the area — and the link between them is the coverage printed on the tin. This calculator is the general one: give it any area, any coats, any coverage, and it tells you the paint.
For a room, use the wall paint or ceiling paint calculators, which work the area out from the room size and deduct doors and windows.
Your results
Enter your measurements and press Calculate.
Quantities are rounded up to whole tiles, planks, boxes or bags, after the wastage allowance. Cost appears only when you enter a price.
Formula
All lengths are converted to a single unit before the calculation: 1 ft = 0.3048 m, 1 in = 25.4 mm, 1 ft² = 0.09290304 m², 1 yd² = 9 ft². Material quantities are rounded up — you cannot buy part of a tile, plank or bag.
How to use this calculator
- Measure or calculate the area to paint.
- Enter the number of coats (usually 2).
- Enter the coverage from the tin — this is the number that matters most.
- Add a price per gallon or litre if you want a cost estimate.
Worked example
| Area | 381 ft² |
|---|---|
| Coats | 2 |
| Coverage | 350 ft² per gallon |
| Paint needed | 381 × 2 ÷ 350 = 2.18 gallons (8.24 litres) |
| To buy | ⌈2.18⌉ = 3 gallons |
| Cost at $45 per gallon | 2.18 × $45 = $98.10 (exact paint used) |
Check it by hand: every step above uses the formula in the box. If your numbers match the example inputs but the calculator gives a different answer, please report it via the contact page.
Frequently asked questions
How much paint do I need per square foot?
It depends on the paint's coverage, which is printed on the tin — typically 300–400 sq ft per gallon (7–10 m² per litre). Divide your area (times coats) by that coverage. This calculator does it, and it never assumes a coverage for you.
Should I buy the exact amount or round up?
Round up to whole gallons or litres — paint is sold in whole tins. The calculator shows both: the exact amount the job needs, and the whole tins to buy. Keep the leftover for touch-ups.
How many coats of paint do I need?
Two coats is standard for a proper finish, especially over a different colour or new plaster. One coat can work when repainting the same colour in good condition.
Does paint coverage include wastage?
Coverage figures from the tin already allow for normal application losses on a smooth surface. Rough or porous surfaces (new plaster, bare wood) absorb more — allow an extra coat or 10% more paint.
Related calculators
Estimates only. Results are for planning. Measure twice, confirm box coverage and tile sizes on the packaging you buy, and follow the manufacturer's instructions. See the disclaimer.