Paint Calculator
How much paint do I need?
Enter the room's size and how many coats you're planning. We subtract doors and windows, add the ceiling if you're painting it, and round up to the gallons to buy.
Keep a little from the same batch for touch-ups.
- Paint needed
- 1.9 gallons
- Wall area
- 333 sq ft
An estimate to plan and budget with. Measure carefully and check the product’s own figures before you buy.
Results update as you type.
How it’s calculated
- 1
Wall area is the room's perimeter times the wall height: 2 × (length + width) × height.
- 2
We subtract about 21 sq ft for each door (3 × 7 ft) and 15 sq ft for each window (3 × 5 ft).
- 3
Paintable area × coats ÷ coverage per gallon gives the gallons, which we round up to whole cans.
Before you buy
Primer counts as a coat: use it over new drywall, stains, or a dark color you're covering.
Textured or porous walls drink more paint; plan on the low end of the coverage range.
Buy all your paint at once so the color matches from can to can.
Questions
How much paint do I need for a 12 × 12 room?
With 8 ft walls, one door and two windows, the walls are about 333 sq ft. Two coats at 350 sq ft per gallon is about 1.9 gallons, so buy 2 gallons. Add about 1 gallon if you're painting the ceiling too.
Do I need two coats of paint?
Usually. Two coats give even color and better durability. One coat can be enough when you're repainting the same color over a clean, sound surface.
How many square feet does a gallon of paint cover?
Most interior wall paint covers about 350 to 400 sq ft per gallon on smooth, primed walls. Rough or unprimed surfaces cover less.