FREE CALCULATOR · ESTIMATE ONLY
Paint calculator.
How many gallons for the walls, after doors and windows, for the number of coats you plan.
TL;DR
Enter the total length of the walls, the wall height, the number of doors and windows, the coats and the coverage on the can. The calculator gives the paintable area and the gallons to buy, rounded up, plus a paint cost if you add your price per gallon.
Add up every wall. A 12 × 12 room is 48 ft.
About 20 sq ft each
About 15 sq ft each
From the can. Often 350–400.
Your numbers
Estimate only. Walls only, no ceilings or trim. Textured walls, dark colors, bare drywall and primer all use more paint. Labor isn't included.
THE MATH
How it works.
- Wall area = total wall length × wall height.
- Subtract about 20 sq ft per door and 15 sq ft per window.
- Gallons = paintable area × coats ÷ coverage per gallon, rounded up.
- Paint cost = gallons × your price per gallon.
NEXT STEP
Turn the rough number into a real estimate.
The free Peak estimate tool lays out options, takes the signature and collects the deposit.
QUESTIONS
Common questions.
With 8 ft walls, one door, two windows and two coats at 350 sq ft per gallon, about 1.9 gallons, so buy 2. Ceilings and trim are extra.
Many wall paints say 350 to 400 square feet per gallon. Check the can. Rough or porous walls take more.
No, walls only. Run the ceiling separately using its area.
Try the Peak tools.
Leads, estimates, invoices, jobs and photos, with Sherpa doing the office work.
Sign-up opens soon. The demo is open now, with made-up data, no sign-up needed.