How Much Paint for a 10x10, 12x12 or Any Size Room

Room sizes worked out in advance

Below the calculator, a chart lists the paint for rooms from 8 × 10 ft to 16 × 20 ft with 8 ft walls, and from 3 × 3 m to 5 × 6 m with 2.4 m walls, in three columns: walls only, the ceiling only, and both. Each has a one-coat and a two-coat figure, so you can see what a quick refresh costs against a full repaint. Every figure comes from the same maths as the paint calculator: walls are measured as perimeter × height, less one door and one window; the ceiling is the floor area; and the paint is the area times the coats, divided by 400 sq ft per gallon or 10 m² per litre.

The calculator above starts with a 10 × 10 ft room. Press Open on any row of the chart to load that size instead, then adjust it: real rooms rarely have exactly one door and one window.

Reading the chart

Paint is sold in whole cans, so round up. The chart shows the exact amount because two rooms’ leftovers can add up to a whole can when you paint them from the same one; the calculator adds rooms together and picks the cans for the total. The second table does that per paint: for each size it lists the tins with the least paint left over in one wall paint from each maker, at the coverage that maker publishes. Makers’ figures are for smooth, sealed walls, so bare plaster or a strong colour change can take more; the one-wall calculator covers a single feature wall and the ceiling calculator a ceiling on its own.

Paint by room size

One door (32 × 80 in or 762 × 1981 mm) and one window (3 × 4 ft or 1.2 × 1.2 m) taken off the walls, at 400 sq ft per gallon or 10 m² per litre. Open puts that room in the calculator above, where you can change anything.

The cans, paint by paint

Walls and ceiling, two coats, in one wall paint from each maker at the coverage it publishes (checked September 2026), bought in that paint's own sizes with the least left over. A paint that covers more per litre needs fewer or smaller tins for the same room.

Coverage from each maker's product page or data sheet, linked on its page: Dulux (UK), Benjamin Moore (US), Sherwin-Williams (US), Behr (US), Crown (UK), Valspar (UK), Farrow & Ball (UK), Jotun (UAE), Valspar (US), Glidden (US), Dunn-Edwards (US), Dulux (Canada), Dulux (Australia), Taubmans (Australia), Haymes (Australia), Wattyl (Australia), Dulux (New Zealand), Dulux (South Africa), Plascon (South Africa), Asian Paints (India), Berger (India), Nippon Paint (Malaysia), Boysen (Philippines). Brand names are used only to describe the products; Meadow Tools is not affiliated with any of them.