Paint Calculator: The Complete Guide
Estimate how much paint to buy. Enter your total wall area and how many coats you're applying to get the gallons or litres needed, based on typical coverage.
Who the Paint Calculator is for
DIYers and decorators planning an interior or exterior paint job.
How to use the Paint Calculator
- Type your values into the fields above — pick your currency or units where the calculator offers them.
- Results update automatically as you type; there's no submit button and nothing is sent to a server.
- Adjust any input to compare scenarios, then copy the result with a single click.
How it works
Paint needed = wall area × coats ÷ coverage. Typical coverage is about 350 sq ft per gallon, or roughly 10 m² per litre.
Features
- Gallons or litres
- Accounts for coats
- Imperial or metric
- Typical coverage rates
Estimating paint
Paint coverage depends on the surface and product, but about 350 square feet per gallon (or 10 m² per litre) is a good rule for smooth interior walls. Multiply your wall area by the number of coats and divide by coverage. Porous or textured surfaces soak up more, so round up and keep some for touch-ups.