Paint Coverage Calculator
Short answer: A typical 12 by 12 foot room with 8 foot walls, one door and two windows needs about 2 gallons of paint for two coats, at the common label rate of 350 square feet per gallon.
How is this calculated?
Wall area is the room perimeter times the wall height. The calculator subtracts about 21 square feet per standard door and 15 square feet per average window, multiplies by the number of coats, and divides by the coverage on your paint can. Labels commonly list 250 to 400 square feet per gallon; rough, porous or freshly patched walls land at the low end. Buy an extra quart for touch-ups.
Frequently asked questions
How many square feet does a gallon of paint cover?
Most interior wall paints list 250 to 400 square feet per gallon per coat. Check the label on the can you are buying and enter that number. Textured or unprimed drywall uses more paint.
Do I need two coats?
Plan on two coats for a color change, a dark color, or new drywall. One coat can be enough when you repaint the same color over a clean, sound finish.
Should I prime first?
Prime new drywall, drywall patches, stains and glossy surfaces. Primer on patched spots keeps them from showing through as dull patches.