How to calculate paint needed
Wall area is calculated from the perimeter of the room multiplied by wall height. Approximate door and window areas are subtracted before multiplying by the number of coats.
Paint calculation example
If the total paintable wall area is 500 square feet and you apply two coats, you need 1,000 square feet of coverage. At 350 square feet per gallon, that is approximately 2.86 gallons.
Why paint coverage varies
Coverage can vary with paint type, surface texture, primer, color change, application method and how absorbent the surface is.
Manufacturer coverage figures are more reliable than a generic estimate for final purchasing.
Frequently asked questions
How much area does one gallon of paint cover?
Coverage varies by product. The calculator starts with 350 square feet per gallon, but you can change this value.
Does the calculator account for doors and windows?
Yes. Approximate areas are deducted based on the number entered.
How do multiple coats affect paint quantity?
Two coats require approximately twice the coverage of one coat.
Should I buy extra paint?
A small extra amount can be useful for touch-ups and variation in actual coverage.