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Paint Coverage Calculator
Estimate how much paint to buy for walls, trim, or exterior surfaces before you price the job.
KNOW THE MATH
A number you can explain.
Gallons = net surface area × coats × (1 + waste %) ÷ product coverage. Round up for each product and color.
Our methodology & assumptions WORKED STARTING EXAMPLE
3 gallons
- Net paintable area
- 333 ft²
- Paint before rounding
- 2.09 gal
- Purchase cost
- $135.00
- (420 − 42 − 45) = 333 ft² of surface.
- 333 ft² × 2 coats × (1 + 10%) ÷ 350 ft²/gal = 2.09 gal.
- Round up to 3 whole US gallons at $45.00/gal.
Before you quote
Do I enter wall area or floor area?
Enter the surface you will actually paint. For a rectangular room, wall area is 2 × (length + width) × height. A 12 × 10-foot room with 8-foot walls has 352 ft² of wall area before subtracting openings.
Does this include primer or different colors?
This calculation covers one finish product and color. Calculate primer and other colors separately using their own coat count and product coverage.
Which coverage rate should I use?
Use the coating manufacturer's technical data sheet, then adjust for texture, porosity, application method, and your experience. The starting value is an example, not a product specification.
Estimating framework: Painting Contractors Association. This tool's starting values are editable examples, not rates published by PCA.