Find wall or surface area, with an option to subtract a single opening. Use your paint manufacturer's coverage rate to estimate how much paint you need.
Enter measurements in any unit. Add quantity, waste factor, and material price if you need them.
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See area in ft², in², yd², m², and acres, plus a cost estimate when you enter a price.
Frequently Asked Questions
How do I calculate square footage for painting?
Measure height and width of each wall. Multiply for each wall and add. Subtract windows and doors. Wall with Window subtracts openings for you.
How much paint do I need per square foot?
One gallon covers about 350 to 400 sq ft per coat. For two coats, divide total wall area by 175 to 200. Example: 800 sq ft ÷ 175 ≈ 4.5 gallons for two coats.
Should I subtract windows and doors from wall area?
Yes. A standard door is about 21 sq ft (3 × 7 ft). A standard window is about 12 sq ft (3 × 4 ft). Subtract those from total wall area, or use Wall with Window to do it automatically.
How do I calculate paint for exterior walls?
Measure length and height of each exterior wall and multiply. Subtract windows and doors. Add all walls. Exterior coverage is similar to interior (350 to 400 sq ft per gallon), but texture can need up to 50% more paint.
How do I calculate paint for a room with vaulted ceilings?
For the sloped wall, use Cathedral Wall. Enter base width, left wall height, and right wall height. The calculator applies the trapezoid formula for that surface.