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Paint Quantity Calculator
Metric measurements. Doors and windows are deducted at standard allowances; adjust the coverage to match your tin.
Deducts 1.8 m² per door and 1.5 m² per window. Ceiling area is shown separately and is not included in the paint estimate.
The arithmetic
Wall area = 2 × (length + width) × height. Subtract 1.8 m² for each door and 1.5 m² for each window, multiply by the number of coats, then divide by coverage. Cans are rounded up to 5 L.
When to add a coat
New plaster, bare wood and dramatic colour changes absorb more paint. If any of those apply, set coats to three and check the result against the tin before buying.
Frequently asked questions
Why subtract doors and windows?
They are not painted, and leaving them in overstates the area. The standard allowances are approximations; measure unusually large openings if the room has them.
Does primer count as a coat?
No. Primer has different coverage and is usually calculated separately. Add it as an extra purchase rather than a paint coat.
What about trim and doors?
They use a different paint and a much smaller quantity. This calculator covers walls only.