Paint Calculator
Estimate how much paint you need: enter wall area in square feet and coats, get gallons to buy and the exact coverage math.
About this tool
This paint calculator converts wall area into gallons of paint using the industry-standard coverage of 350 sq ft per gallon per coat. Enter your total wall area, the number of coats and it tells you exactly how many gallons to buy.
Measure each wall's width times height, add them, subtract roughly 15 sq ft per window and door — then let the calculator handle the math. Buying one extra gallon saves a second store trip later, and leftover paint is the perfect touch-up supply.
FAQ
How much area does one gallon cover?
A gallon of typical interior paint covers about 350 sq ft (32 m²) per coat. High-end or textured paints cover less.
How do I measure wall area?
Multiply the width and height of each wall and add them up. Subtract window and door openings roughly, or keep them for safety.
Should I round up the paint amount?
Yes — buy whole cans and keep the leftover for touch-ups. It is cheaper than a second purchase for one wall.