How much paint a ceiling takes
Length times width, times the coats, over what a gallon covers. A 12 by 12 foot ceiling is 144 square feet; two coats at 350 square feet a gallon is 288 over 350, 0.82 gallons. Buy one gallon can: in quarts it would take four, at nearly twice the price.
The page asks for the room the ceiling is in, and on this page only its length and width count. The room keeps the rest — an 8 foot wall height, a door and a window — without asking for it, so the walls can be added later without measuring again: switch "What to paint" and the boxes come back with the room's numbers in them. A ceiling that is not a whole room, a hallway's or a bay's, is a rectangle: its width by its length.
Ceilings by size
| Ceiling | Area | Two coats buys |
|---|---|---|
| 5 × 8 ft bathroom | 40 ft² | 1 qt |
| 8 × 10 ft | 80 ft² | 2 qt |
| 10 × 10 ft | 100 ft² | 1 gal |
| 12 × 12 ft | 144 ft² | 1 gal |
| 14 × 16 ft | 224 ft² | 1 gal + 2 qt |
A quart covers about 100 square feet, by Sherwin-Williams' figure, so a small bathroom ceiling is a quart even with two coats. Past two quarts a gallon can costs less than three of them at the prices this page starts with; type your store's beside each can and the cheapest mix moves with them.
Measured, not assumed square
Sherwin-Williams' quick calculator adds a ceiling to every room and works it out from the room's perimeter, as if the room were square: a quarter of the perimeter, squared. For a 10 by 14 foot room that is 12 × 12 = 144 square feet where the ceiling is 140. Here the ceiling is the length and the width you type, and it is only added when you ask for it.
Walls as well
Switch "What to paint" to walls and ceiling and the same room's walls join it, out of the same cans: the 12 by 12 room with a door and a window is then 493 square feet, 2.82 gallons, three cans. If the ceiling is a different paint from the walls, keep the two apart and buy each on its own page.
Prices are our own estimates, not a store's. We are not connected with any brand or store named here.