Estimate how much paint you need for a given wall area and number of coats.
Calculated instantly in your browser.
How do you calculate how much paint you need?
Paint needed = area × coats ÷ coverage, with typical coverage about 350 ft² per gallon or 11 m² per litre. For example, a 400 ft² wall with 2 coats at 350 ft²/gallon needs about 2.5 gallons. Subtract doors and large windows from the area for a closer estimate, and buy a little extra for touch-ups.
Understanding your result
Subtract doors and large windows from the area for a closer estimate, and buy a little extra for touch-ups.
Formula and method
Paint needed = area × coats ÷ coverage. Typical coverage is about 350 ft² per gallon or 11 m² per litre.
Assumptions and limitations
The estimate uses the area, coats and coverage you enter and assumes smooth walls. Real usage varies with surface texture, colour changes needing more coats, porous or bare surfaces, and application method, so buy a little extra for touch-ups. It does not cover primer, trim or ceilings separately unless you calculate those areas too.
Worked example
A 400 ft² wall with 2 coats at 350 ft²/gallon needs about 2.5 gallons.
How to use this tool
- Enter the wall area to paint.
- Set the number of coats and the coverage.
- Press Calculate.
About the Paint Calculator
The Paint Calculator estimates how much paint a job needs based on the wall area, the number of coats and the paint’s coverage.
Who should use this tool
Homeowners, decorators and landlords planning a repaint who want to buy roughly the right number of tins. Useful for a single feature wall or a whole room, and for checking a decorator's material estimate before agreeing to a job.
Benefits
- Estimates paint from area, coats and coverage
- Helps you avoid running out mid-job
- Accounts for multiple coats in one calculation
- Free in the browser with no sign-up
Practical use cases
- Working out tins for a single room repaint
- Estimating paint for a feature wall
- Checking a decorator's material estimate before agreeing
- Budgeting paint before visiting the shop
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Frequently asked questions
How many coats do I need?
Two coats is typical for good coverage. Dark colours or big colour changes may need a primer plus two coats.
Should I subtract doors and windows?
For a closer estimate, yes. Subtracting large openings such as doors and picture windows avoids overbuying, especially in small rooms. Small windows make little difference and are often left in as a built-in margin. Keeping a little spare paint is wise for later touch-ups regardless.
Does a darker colour need more paint?
Often, yes. Covering a light wall with a strong or dark colour, or vice versa, can need an extra coat for an even finish, which increases the total. Priming first and using the coat count in this tool to reflect that will give you a more realistic quantity.