Estimate paintable wall area, gallons of paint needed, and total coverage using room dimensions, wall height, doors, windows, number of coats, and paint coverage rate.
Wall area formula:
Perimeter × wall height = total wall area
Paint formula:
(Paintable area × coats) ÷ coverage rate
This calculator can also include ceiling area and add extra material for waste or overage.
Knowing how much paint you need helps when planning room painting projects, budgeting, buying supplies, and reducing waste from overbuying or underbuying.
Adding extra paint is often useful for second coats, texture, touch-ups, and uneven coverage.
Your paintable area is the estimated surface area after subtracting doors and windows. The total paint needed depends on the number of coats, the coverage rate, and any extra percentage added.
The estimate helps you decide how much paint to buy for walls or walls plus ceiling. Always check the paint can label for the manufacturer’s actual coverage recommendation.
Estimate the paintable surface area, multiply by the number of coats, then divide by the paint coverage rate.
Usually yes. Subtracting larger openings can make the estimate more accurate, especially for single-room projects.
Many paints cover around 300 to 400 square feet per gallon, but the actual amount varies by product and surface.
Yes for many projects. Extra paint helps with waste, second coats, touch-ups, and future repairs.