Paint calculator
How much paint do you need? Enter your room, subtract the openings, pick your coats: get gallons, not guesses. Free, instant, no signup.
You need to paint
: sq ft of wall
Buy
:
How the math works
Wall area is the room perimeter times the ceiling height: 2 × (length + width) × height. Subtract about 21 sq ft per door and 15 sq ft per window. Multiply by the number of coats, divide by your paint's coverage per gallon (350–400 sq ft for most interior paints), and round up to quantities you can actually buy: gallons first, then a quart if the remainder is small.
Two tips that save real money: going from a dark color to a light one usually needs a tinted primer plus two coats, and textured or never-painted drywall absorbs 10–15% more paint than the can promises.
Paint needed by room size
8 ft ceilings, one door, one window, two coats at 375 sq ft/gallon.
| Room size | Wall area | Paint to buy |
|---|---|---|
| 10 × 10 ft | 320 sq ft | 1 gal + 1 qt |
| 12 × 12 ft | 384 sq ft | 2 gal |
| 12 × 16 ft | 448 sq ft | 2 gal + 1 qt |
| 15 × 15 ft | 480 sq ft | 2 gal + 1 qt |
| 15 × 20 ft | 560 sq ft | 3 gal |
| 20 × 20 ft | 640 sq ft | 3 gal + 1 qt |
Not sure which color?
Upload a photo of your room and see it repainted in any style before you buy a single can.
Try the AI redesign: freeOr explore color palettes for your room first.