Interior surfaces
Paint Calculator
Enter the wall area you're painting and how many coats. A gallon covers about 350 square feet per coat on a smooth, primed surface.
At a glance
- Covers per gallon
- 350 sq ft
- Waste allowance
- +5%
- Answer in
- gallons
100 sq ft needs:
1 gallons
Includes a 5% allowance for waste.
About 350 sq ft per gallon per coat. Bare drywall, deep color changes, and rough textures drink more, so subtract large windows and doors from your area.
Interior surfaces
Measure the room, not the wall
Paint, flooring and tile all get bought by total area with an allowance on top, and the allowance is where people come up short. Doorways, closets and cuts add up faster than the walls do.
How this is worked out
No hidden fudge factor. This is the whole calculation.
- Length times width gives the area in square feet.
- That area is divided by 350 square feet, which is what one covers, to give the gallons.
- Coats multiplies the total.
- A 5% allowance is added on top for cuts, offcuts and odd shapes.
- The total rounds up, since you cannot buy part of a gallon.
Common questions
- How much paint do I need?
- Enter the wall area you're painting and how many coats. A gallon covers about 350 square feet per coat on a smooth, primed surface. Enter your measurements above and this calculator gives you the amount, including a waste allowance where it applies.