Paint Calculator
Gallons needed for walls, doors and windows deducted.
Enter your values
ⓘ Live results
Results
- Paint needed
- 2.42 gallons
- Buy
- 3 gallons
- Paintable wall area
- 453 sq ft
- Primer if bare drywall
- 1.51 gallons
Quick answer
One US gallon of paint covers about 350–400 square feet per coat on primed drywall.
Gallons = wall area × coats ÷ 375
How to use the Paint Calculator
- 1Measure the perimeter of the room.
- 2Enter the wall height and openings.
- 3Choose how many coats you plan to apply.
Worked example
Using the values the calculator loads with:
Inputs
- Room perimeter60 ft
- Wall height9 ft
- Doors2
- Windows3
- Coats2
Results
- Paint needed2.42 gallons
- Buy3 gallons
- Paintable wall area453 sq ft
- Primer if bare drywall1.51 gallons
Frequently asked questions
How much does a gallon cover?
About 375 sq ft per coat on smooth primed walls; textured or porous surfaces can drop to 250 sq ft.
Do I need primer?
Yes on bare drywall, over strong colour changes and on stained or patched areas — otherwise a self-priming paint is fine.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.