Ceiling Paint Coverage Calculator
Calculate how much paint a ceiling needs from its dimensions, the number of coats and the coverage on the tin — plus gallons to buy and the cost.
How it works
Area = L × W · Painted = area × coats · Gallons = ceil(painted ÷ coverage) · Cost = gallons × price
A ceiling is a simple rectangle, so its area is just length times width — no windows or doors to subtract. Multiply by the number of coats (two is standard, and ceilings often need two because of the flat sheen and the awkward angle you view them from), then divide by the coverage printed on the tin. Flat ceiling paints usually cover 300–400 ft² per gallon; textured or previously unpainted surfaces sit at the lower end because they soak up more.
Worked example
A 12 × 10 ft ceiling is 120 ft². Two coats means painting 240 ft². At 350 ft² per gallon that is 240 ÷ 350 = 0.69 gallons — so a single gallon covers it with paint to spare for touch-ups.
Frequently asked questions
How many coats does a ceiling need?
Two is the norm. Ceilings show roller marks and patchiness under raking light, and a single coat rarely hides the old colour or the repairs evenly. Bare drywall or a colour change almost always needs two.
Why does ceiling paint cover less than wall paint sometimes?
Flat ceiling finishes and textured or freshly skimmed surfaces absorb more paint than smooth, sealed walls. If the ceiling has never been painted, prime it first or expect coverage nearer 300 ft² per gallon.
Should I subtract for a light fitting?
No — the area of a fixture is tiny and you paint right up to it. Keeping the full rectangle also builds in a small, useful buffer for cutting in around edges and fittings.
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This calculator is for educational purposes. Double-check important results before acting on them.