How Much Paint Per Square Foot?
One gallon of paint covers about 350 to 400 square feet in a single coat on a smooth, primed surface. Because most jobs need two coats, plan on roughly 200 square feet of finished wall per gallon. Measure the wall area, multiply by the number of coats, and round up to the next whole gallon.
Measuring the walls
Add up each wall's height times width. You can subtract large doors and picture windows, but leaving small windows in gives a useful margin.
Rough or porous surfaces (bare drywall, masonry) drink more paint and cover toward the lower end of the range.
Coats and primer
Two coats give even color and better durability, and are standard for a color change. Add a primer coat over bare surfaces, patches, or big color shifts.
Paint comes in quarts, gallons, and 5 gallon buckets; buckets are cheaper per gallon for big jobs. The paint calculator turns your wall area and coats into gallons.
FAQ
How much does a gallon of paint cover?
About 350 to 400 square feet in one coat on a smooth, primed surface; less on rough or porous walls.
How many gallons of paint for a 12x12 room?
About 2 gallons for two coats on 8 ft walls, before subtracting doors and windows.