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Enter the room dimensions to estimate how many gallons of paint you'll need.
Buying the right amount of paint saves money and avoids a second trip to the shop halfway through a wall. Mixing two batches can also leave a visible colour difference. The calculator works out the paintable wall area of a room, takes off doors and windows, multiplies by the number of coats, and divides by your paint's coverage.
Most interior paints cover around 350–400 sq ft per US gallon per coat on smooth, primed walls. Check the tin, because rough, porous or freshly plastered surfaces can absorb much more.
A 12 × 10 ft bedroom with 8 ft walls, one door and two windows, two coats, paint covering 350 sq ft per gallon:
One US gallon is about 3.785 litres, so the 1.72-gallon example above is about 6.5 L. Metric tins usually state coverage in m² per litre (often 12–16 m²/L). Use the Unit Converter to switch between sq ft and m².
Usually, yes. Two coats give even colour and better durability, especially when changing colour. A big jump, such as dark to light, may need a primer first or a third coat.
No, it calculates walls only. For a ceiling, multiply length × width and work that out separately, as ceiling paint often has a different coverage rate.
About 10% extra for touch-ups, and round up to the next whole tin. Keep the leftover, labelled with the room and colour code, for future repairs.