Paint Calculator
Find out exactly how many gallons of paint you need for your room.
Room Dimensions
Enter room length and width to see your estimate.
How We Calculate Paint Coverage
Our calculator uses the standard paint coverage rate of 350 square feet per gallon, which is the industry average for a single coat of interior latex paint on a smooth surface.
The formula is straightforward:
- Wall area = 2 × (length + width) × height
- Subtract openings: each standard door is ~21 sq ft, each window is ~15 sq ft
- Multiply by coats: most jobs need 2 coats for even coverage
- Divide by 350 sq ft/gallon and round up
Tips: Textured walls, porous surfaces, and dark-to-light color changes may require extra paint. We recommend buying an extra quart for touch-ups down the road.