Paint Calculator
Work out how much paint a room needs from its dimensions, doors, windows, and number of coats.
Room dimensions
Openings & coats
How this is calculated
Wall area is the room's perimeter times its height (2 × (length + width) × height), minus a standard deduction for each door (≈1.6 m²) and window (≈1.5 m²). That paintable area is multiplied by the number of coats, then divided by a typical coverage rate of 10 m² per litre to get the amount of paint. Actual coverage varies by paint brand and wall texture — check the can for the exact figure if you have it.
Common questions
Does this include the ceiling?
No — this covers walls only. Ceilings are usually painted with a different (flatter) finish; add its area (length × width) separately if you're painting it too.
What if my paint covers a different area per litre?
The 10 m²/L figure is a typical average for a single coat on primed drywall. Cheaper paints and unprimed or textured walls often cover less — check the manufacturer's label and scale the result if it differs meaningfully.
Part of Home Improvement Calculators