Ceiling Paint Calculator

Painting only the ceiling

On this page every room in the paint calculator starts with its walls switched off, so the result is ceiling paint alone. Enter the length and width of each room; the ceiling height box is still there, but it only counts once you switch Walls back on. Add a room for every ceiling you’re painting, or use Add it as a room if you drew the room in the room planner: the planner’s L-shape comes across as well.

A ceiling’s area is its floor area. Further down, a table lists ceiling paint for everyday room sizes at two coats and the same coverage the calculator starts with, so you can check a figure before you measure.

Coverage of ceiling paint

Benjamin Moore sells its ceiling paint as an ultra flat finish, but the amount you need works the same way as for walls: area times coats, divided by what one litre or gallon covers. Benjamin Moore’s data sheet for Waterborne Ceiling Paint gives 400 to 450 sq ft per gallon, “depending on surface texture and porosity”. Dulux Trade’s figure for Supermatt, up to 18 m² per litre, is a best case for smooth, sealed plaster. A textured or popcorn ceiling, fresh plaster or a stain you are covering takes more, so start low and add a coat of primer (tick Primer first) over new plaster or patches.

Walls and ceiling in one go

Switch Walls on in each room and tick the box Ceiling in a different paint, so the ceiling is planned in a paint of its own: the calculator gives the wall paint and the ceiling paint as separate lines, each with its own cans, and the doors and windows come off the walls only. Paint the ceiling first, so drips land on walls you haven’t painted yet.

Ceiling paint for common room sizes

Two coats, at 400 sq ft per gallon or 10 m² per litre. Round up to whole cans; the calculator picks them for you.

Sources, checked September 2026: Benjamin Moore, Waterborne Ceiling Paint 508 data sheet (400–450 sq ft per gallon); Dulux Trade, Supermatt (up to 18 m² per litre).