Find how many gallons of paint your project needs. Each dimension has its own unit selector (in/ft/yd/m).
Paint is estimated by area and coverage. Measure each wall (length times height, any unit), and add them up. A gallon covers about 350 sq ft on smooth walls - less on texture or porous surfaces, so use the coverage preset. Multiply the area by the number of coats and divide by coverage. Two coats is standard.
Use the paint calculator to estimate gallons from paintable area, coverage rate and coat count. It is suited for walls, ceilings, siding sections and other surfaces where coverage is quoted in square feet per gallon.
Start with the calculator that matches how your material is sold: area, length, volume, count, weight or electrical load. Enter one work area at a time, use the unit selector beside each measurement, then review the order quantity and cost fields before comparing supplier quotes.
Most calculators can save the current estimate in your browser, reload named estimates, print a copy, switch to dark mode or create a shareable link. Those tools are intended for planning and communication; always confirm final quantities, coverage rates, density, code requirements and pricing with the supplier or contractor responsible for the work.