Paint planning
How Much Paint Does a Room Need?
Most bedrooms and living rooms need 2 to 3 gallons of wall paint for two coats. The exact amount is wall area, minus doors and windows, times the number of coats, divided by the coverage on the can, which is usually 350 to 400 square feet per gallon.
Open the paint calculatorStep 1: measure the wall area
Add the length of every wall to get the room perimeter, then multiply by the ceiling height. A 12 x 14 foot room has a 52 foot perimeter. With 8 foot ceilings that is 416 square feet of wall.
Subtract about 20 square feet for each standard door and about 15 square feet for each average window. With one door and two windows, the same room has 366 square feet to paint.
Step 2: multiply by coats and divide by coverage
Two finish coats are normal, so the 366 square foot room needs 732 square feet of coverage. Add 10 percent for roller loss and touch-ups and you reach about 805 square feet.
Divide by the coverage on the label. At 350 square feet per gallon, 805 square feet is 2.3 gallons, so you buy 3 gallons, or 2 gallons and a quart if the store sells your color in quarts.
| Surface | How to measure | Notes |
|---|---|---|
| Walls | Perimeter x ceiling height | Subtract doors and windows |
| Doors | About 20 sq ft each | Subtract from walls, or add if painting the door |
| Windows | About 15 sq ft each | Measure large picture windows directly |
| Ceiling | Room length x room width | Usually a separate flat ceiling paint |
| Trim and baseboard | About 1 quart per average room | Use a trim enamel, not wall paint |
What changes the number
Coverage on the label assumes a smooth, sealed, similar-colored surface. Real walls are often less cooperative, so adjust before you shop.
- Textured or unpainted walls soak up more paint. Drop coverage to 250 to 300 square feet per gallon.
- Dark-to-light color changes often need primer or a third coat.
- Vaulted or 9 to 10 foot ceilings add wall area quickly. Measure the real height.
- Painting the ceiling the same color adds length times width to the total.
Buy it all at once
Tinted paint can vary slightly from batch to batch. Buy the full amount for a room in one trip, and if you have several gallons of the same color, pour them into one large bucket and mix them before you start. Keep the label or formula sticker so a later touch-up quart matches.
- Wall area is perimeter times height, minus about 20 square feet per door and 15 per window.
- Multiply by two coats, add 10 percent, and divide by 350 to 400 square feet per gallon.
- Ceilings, trim, and primer are separate from the wall paint number.
Run the numbers
The Paint Calculator applies this math to your own measurements and shows each step. Best for a quick store run before painting one room or several similar rooms.