MEASURE
1. The easiest measurement in the house
Length × width of the room, nothing to subtract — ceilings have no doors or windows. A 12×12 bedroom has a 144 sq ft ceiling; a 15×20 living room, 300 sq ft.
COVERAGE
2. Ceilings consume slightly more than walls
Same base reference — 350 sq ft per gallon per coat — but ceilings work against you: short overhead passes, stipple texture and drips add loss. Plan 15% waste instead of the usual 10%.
| Room | Ceiling area | Buy |
|---|---|---|
| Bedroom 12×12 | 144 sq ft | 1 gallon |
| Living 15×20 | 300 sq ft | 2 gallons |
| Whole floor 1,000 sq ft | ≈ 1,000 sq ft | 5-gallon pail |
Flat white interior latex — the same can of wall paint works; a flat finish hides imperfections.
BUY
3. How much to buy per room
A 12×12 ceiling at two coats with the 15% margin takes about 1 gallon. A whole 1,000 sq ft floor plan carries roughly the same area in ceiling: about 3.3 gallons at two coats — a 5-gallon pail covers it with margin for touch-ups.
TECHNIQUE
4. One trip up the ladder
An 18 mm (3/4 inch) nap roller on an extension pole, crossed passes, and raking light: ceiling marks hide from straight-on but glare from the side. Cut in the edges with a brush before each strip, and paint the ceiling before the walls — drips on unpainted drywall do not matter.
Ready to skip the math?
Open the paint calculator