Paint Calculator
Enter your room size to see how many gallons of paint you need, with doors, windows and extra coats included.
These are estimates. Real jobs vary with surface, product and waste, so round up and check your product's label before you buy.
How much paint do I need for a 12×12 room?
A 12×12 room with 8-foot ceilings, one door and two windows has about 334 square feet of wall to paint. Two coats at the typical coverage of 350 square feet per gallon comes to about 1.9 gallons, so buy 2 gallons. This table uses the same assumptions for other common rooms (walls only).
| Room size | Wall area (sq ft) | Gallons, 2 coats |
|---|---|---|
| 10×10 ft | 270 | 2 |
| 12×12 ft | 334 | 2 |
| 12×14 ft | 366 | 3 |
| 14×16 ft | 430 | 3 |
| 16×20 ft | 526 | 4 |
How the paint calculator works
We multiply the room's perimeter by the ceiling height to get the total wall area, then subtract 20 square feet for each standard door and 15 for each window. Dividing by your paint's coverage rate and multiplying by the number of coats gives gallons. Always round up, and keep a little extra for touch-ups.
Tips for buying the right amount
New drywall, dark colors and big color changes often need primer or a third coat. Rough or textured walls soak up more paint, so lower the coverage number. Buy all your paint at once and mix the cans together so the color stays consistent from wall to wall.
Frequently asked questions
How many square feet does a gallon of paint cover?
Most labels list about 350 to 400 square feet per gallon for one coat. Check your can and enter that number in the calculator.
Does one gallon of paint cover a room?
One gallon can cover one coat in a small bedroom, but most rooms need two coats, which usually means two gallons.
Should I include the ceiling?
Tick the ceiling box only if the ceiling gets the same paint as the walls. Ceilings are often painted separately with flat ceiling paint.