Paint Coverage Calculator
Save money and avoid extra trips to the store by calculating exactly how much paint you need before starting your project. Enter the total wall area, number of coats, and the paint's coverage rate, and this calculator tells you the precise number of gallons to buy. It also lets you subtract standard doors and windows from the total area.
The paint calculation formula:
Gallons = (Paintable Area × Number of Coats) / Coverage Rate
- Paintable Area = Total wall area minus doors (≈21 ft² each) and windows (≈15 ft² each)
- Number of Coats: Most paint jobs need 2 coats. Dark-to-light color changes may need 3+.
- Coverage Rate: Standard interior latex paint covers about 350 ft²/gallon on smooth surfaces.
Coverage rate varies by paint type and surface texture:
- Interior latex, smooth wall: 350-400 ft²/gal
- Exterior latex: 250-350 ft²/gal
- Textured surfaces: 200-300 ft²/gal
- Primer: 200-300 ft²/gal
- High-quality paint: 350-400 ft²/gal
Quick tip for calculating wall area: multiply the room perimeter by the ceiling height. For a 12×14 room with 8-foot ceilings: (12+14+12+14) × 8 = 416 ft².