Paint Coverage
Litres or gallons for walls and ceilings from area, openings, coats, and a coverage you can name — manufacturer-stated or your own — with cans and spare.
How much paint to buy for a room and how many cans that is, traceable to the area you measured, the coats you chose, and the spreading rate on the product.
Example: A 12 × 10 ft room with 8 ft walls, 36 ft² of openings, two coats at 350 ft² per gallon: 1.81 gallons — two 1-gallon cans.
Area times coats,
divided by what the can says.
How the litres are formed, where the coverage figure comes from, and why it is the lower one.
The arithmetic
Paintable area = wall area (perimeter × height, or what you measured) + ceiling − openings. Paint = paintable area × coats ÷ coverage (m² per litre or ft² per US gallon; 1 US gal = 3.785 L). Cans are rounded up to the size you buy and the spare is shown.
Coverage: the product's number
Spreading rate depends on the product, the surface, and the applicator, so it is an input. Two ready-made profiles quote manufacturer documentation: Sherwin-Williams SuperPaint Interior Latex Flat (product data sheet 101.02A, 08/2026: 350–400 sq. ft. per gallon at 4 mils wet) and Dulux Trade Vinyl Matt (product page: up to 17 m² per litre). Where a range is stated the lower figure is used so the estimate does not run short; “up to” figures are optimistic on porous or textured surfaces. For any other paint, enter the coverage printed on the can.
What is not included
Primer or sealer on bare surfaces, trim and doors, touch-up, and a first thinned coat some products specify. Product names identify the document quoted; ARZENTIQ is not affiliated with or endorsed by any manufacturer. Prices are whatever you enter. Inputs stay in your browser; the same four anonymous usage counts as the rest of the site apply.