Paint Calculator
Estimate how much paint you need for a room or wall.
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How it works
Enter the wall dimensions (or total area), the number of coats, and the paint's coverage rate, and the tool works out the total paintable area and divides by coverage to estimate how much paint you need. You can subtract the area of doors and windows so you do not over-buy. It supports metric (m², litres) and imperial (ft², gallons). These are estimates — surfaces and brands vary. All math runs locally in your browser.
paint = (area × coats) / coveragePerUnit
Common use cases
- Estimating paint for a bedroom before a trip to the store.
- Working out coverage for two coats on a feature wall.
- Subtracting doors and windows for a more accurate amount.
Frequently asked questions
How accurate is the estimate?
It is a planning estimate. Real coverage depends on the paint, surface texture, color change, and application method, so buy a little extra to be safe.
Can I account for doors and windows?
Yes. Enter their total area and the tool subtracts it from the wall area before estimating, so you do not buy paint for surfaces you are not painting.
What coverage rate should I use?
Check the paint can — typical figures are around 10–12 m² per litre or 350–400 ft² per gallon per coat. Use the manufacturer's number for the best estimate.