Walls and ceilings

Paint Calculator

Estimate gallons using paintable area, coat count, and the manufacturer's coverage rate. Enter the job dimensions below, then review the guide before ordering.

Paint calculation formula

paintable area x coats / coverage per gallon = gallons

Worked example: For 1,200 sq ft, two coats, and 350 sq ft per gallon, the base need is 6.86 gallons. Adding 10% produces 7.54 gallons, which rounds up to 8 gallons.

Calculate paintable wall area

Multiply each wall's width by height and add the wall areas. Subtract large doors, windows, tile sections, and cabinets when precision matters. Ceiling paint should be calculated separately when the product or sheen differs.

Coverage rates are not guarantees

Coverage printed on a can assumes suitable application and surface conditions. Porous drywall, masonry, dramatic color changes, textured surfaces, and overspray can lower real coverage. Primer is a separate material calculation.

Why full-can rounding matters

Paint is purchased in fixed container sizes, and keeping a small amount from the same batch is useful for touch-ups. Confirm whether the retailer sells quarts or five-gallon pails before finalizing the combination.

Before placing an order

Recheck field measurements, confirm the selected product's actual package coverage or density, and ask the supplier about order increments, minimum quantities, delivery limits, and return rules. Keep unlike products and assemblies in separate calculations.