Paint Calculator

Paintable area (sq ft). Paintable area is the combined surface that will receive this paint. Measure each wall or ceiling, multiply its length by its height or width, and add the areas together. Subtract openings only when appropriate to your takeoff; this calculator does not deduct doors or windows for you.

Number of coats. Enter how many complete coats of this same product you intend to apply. A second coat covers the same surface again, so it increases paint demand without increasing the room’s physical area. Estimate primer or a different finish product separately.

Coverage (sq ft / gallon). Use the coverage stated for your selected paint, in square feet per gallon for one coat. Check the label or technical sheet for the specified substrate and application method. Rough or porous surfaces and changes in film thickness can reduce the area a gallon actually covers.

Waste allowance (%). Enter the percentage you want to add for cutting, handling loss or other conditions specific to this work. Apply it to the measured quantity rather than enlarging the measurements as well. The suggested value is editable, not a universal recommendation; enter zero when no allowance is needed.

The estimated paint is the gallons required for the entered area, coats and allowance. Net paint is the amount before waste, and the added allowance is shown separately. The whole-gallon purchasing estimate rounds the unrounded requirement upward; it is the purchasing figure to compare with available containers. Actual product coverage and package sizes still govern the order.

Base gallons = paintable area × coats ÷ coverage per gallon.
Estimated gallons = base gallons × (1 + waste percentage ÷ 100).

Worked example: 1,200 sq ft × 2 coats ÷ 350 sq ft per gallon = 6.857142… gallons. With 10% waste, the estimate is 7.542857… gallons, displayed as 7.54 gallons. Rounding the unrounded total upward gives a whole-gallon purchasing estimate of 8 gallons.

The entered area must already be paintable area. Doors and windows are not subtracted automatically. Coverage varies by product, substrate, and application method. Check manufacturer instructions; this is an estimate, not a guaranteed purchase quantity.