How this calculator works
A flat ceiling has the same area as the floor, so it multiplies length by width, then by the number of coats, and divides by the paint’s coverage. It adds a waste allowance and rounds up to gallons and quarts you can buy.
The default coverage is 350 sq ft per gallon, the conservative end of the 350–400 sq ft most flat ceiling paints list for a smooth, primed surface. Primer is figured at 300 sq ft per gallon. Drop cloths are 9′ × 12′ and tape is a 60-yard roll.
ceiling area = length × width
gallons = area × coats ÷ coverage × (1 + waste)
primer gallons = area ÷ 300 × (1 + waste)Worked example
A 14′ × 12′ bedroom has 14 × 12 = 168 sq ft of ceiling. Two coats at 350 sq ft per gallon is 0.96 gallons; with 10% waste that is 1.06 gallons, which the list buys as 1 gallon plus 1 quart. Two 9′ × 12′ drop cloths cover the floor.
Tips before you buy
- Paint the ceiling before the walls, so any drips and roller spatter land on walls you have not painted yet.
- Roll across the short dimension of the room and keep a wet edge; stopping halfway leaves lap marks that show in raking light.
- Flat ceiling paint hides small flaws best. Satin or eggshell on a ceiling shows every patch and seam.
- Popcorn and heavily textured ceilings soak up more paint. Lower the coverage figure in the advanced settings to match the can.
Questions
- How much area does a gallon of ceiling paint cover?
- Most flat ceiling paints list 350 to 400 square feet per gallon for one coat on a smooth, primed ceiling. Textured, stained or fresh drywall ceilings take more, so this calculator starts at 350 sq ft.
- Is ceiling paint different from wall paint?
- Ceiling paint is usually a flat, thicker, low-spatter formula made to hide flaws under overhead light. You can use flat wall paint on a ceiling, but it tends to drip and spatter more.
- Do I need two coats on a ceiling?
- One coat is often enough when you refresh a white ceiling in good condition with the same color. Plan on two over new drywall, repairs, water stains after priming, or when changing color.
- Do I need to prime a ceiling?
- Prime new drywall, patched areas and water or smoke stains, using a stain-blocking primer on stains. A ceiling that is already painted and sound usually does not need primer.