How much paint does your room need?
Enter the room's dimensions, deduct doors and windows, pick your coats. Get wall area, paint in litres and a primer estimate - before you stand in a paint shop guessing.
Your estimate
-litres of paint
Paintable wall area-
Area to cover (with coats)-
Coverage rate used-
Primer (fresh/never-painted walls)-
Suggested purchase-
Honest limits: coverage varies by brand and surface - rough or unpainted plaster drinks more paint than a smooth repainted wall. Check the coverage figure printed on your paint bucket (it is always there) and re-run the numbers with it. Buying 10% extra for touch-ups is normal, not wasteful.
How the math works
Wall area = 2 x (length + width) x height, minus about 1.9 m2 (20 sq ft) per door and 1.4 m2 (15 sq ft) per window. Ceiling adds length x width. Paint needed = area x coats / coverage rate. Default rate: 10 m2 per litre (about 110 sq ft per litre) for interior emulsion on smooth plaster - a middle figure across common interior paints.
Example: a 12 x 10 ft room with 10 ft walls, one door and two windows comes to roughly 2.5 litres for two coats - so one 4-litre bucket covers it with margin for a second room or touch-ups.