The formula
Wall area = 2 × (room length + room width) × height − doors/windows. Litres = area × coats ÷ coverage per litre. Tins = litres ÷ tin size, rounded up.
Decorating • UK CALCULATOR
Paint Calculator UK
Work out how much wall paint to buy for a rectangular room. Account for doors and windows, coats, coverage per litre and the tin size you want.
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Your estimate starts here
Enter your measurements and calculate to see materials, quantities and an optional price estimate.
GOOD TO KNOW
How this calculator works
Worked example
A 4 × 3 m room with 2.4 m walls has 33.6 m² gross wall area. Subtract 4 m² of openings, then multiply by two coats.
Check before ordering
This estimates wall paint only, not ceilings, doors, skirting or primer. Coverage varies with product, surface porosity and application. Check the manufacturer’s stated coverage.