Paint Calculator
Enter your room dimensions to get the gallons of paint needed, with doors, windows, and coats accounted for.
How to estimate paint
Wall area is the room's perimeter times the wall height: 2 × (length + width) × height. Subtract roughly 20 square feet per standard door and 15 per standard window if you want a tighter number. Most painters skip this since the extra paint covers trim touch-ups.
Coverage and coats
A gallon covers about 350 square feet per coat on a primed, smooth wall. Two coats is standard for a color change; drop to one for a same-color touch-up, or plan for three when covering a dark wall with a light color.
Paint calculator FAQ
How much wall area does a gallon of paint cover?
Typically 350 to 400 square feet per coat on a smooth wall. Textured or unprimed surfaces may only get 250 to 300 square feet per gallon.
How many coats of paint do I need?
Two coats is standard for a color change. One coat can work for a same-color touch-up; three coats are sometimes needed for light colors over dark walls.
Do I need to subtract doors and windows from wall area?
Yes for accuracy, though many painters skip it since it slightly overestimates paint, which covers trim touch-ups. A standard door is about 20 square feet and a window about 15.