The paint calculator estimates how much paint is needed for walls, ceilings, rooms, trim, or exterior surfaces.
Enter your values in the calculator above, then use the explanations below to understand the result, check assumptions, and compare scenarios.
The paint calculator estimates how much paint is needed for walls, ceilings, rooms, trim, or exterior surfaces. It helps homeowners, painters, contractors, and property managers plan material quantities before buying paint. The estimate depends on surface area, number of coats, paint coverage rate, openings such as doors and windows, and surface condition. A smooth primed wall may cover differently than textured drywall, dark color changes, bare wood, stucco, or masonry, so the calculator should be paired with the coverage guidance on the specific paint product.
Paint quantity is estimated by calculating total surface area, subtracting openings when appropriate, multiplying by the number of coats, and dividing by coverage per gallon. Many interior paints cover roughly 300 to 400 square feet per gallon, but product labels and surface conditions should control the final estimate.
The result gives a planning quantity, not an exact purchase guarantee. Round up to the next practical container size and allow extra for touch-ups, roller loading, surface texture, and color changes. For professional bids, separate wall paint, ceiling paint, primer, trim enamel, and exterior coatings because each product can have different coverage.
A 12 ft by 14 ft room has 8 ft walls and needs two coats on all walls.
Result: Plan on about 3 gallons before adjusting for doors, windows, and touch-up needs.
A ceiling measures 15 ft by 20 ft and needs one coat.
Result: One gallon may cover the ceiling if the surface is smooth and already sealed.
| Coverage area | One coat | Two coats |
|---|---|---|
| 250 sq ft | 0.72 gal | 1.43 gal |
| 500 sq ft | 1.43 gal | 2.86 gal |
| 750 sq ft | 2.14 gal | 4.29 gal |
| 1,000 sq ft | 2.86 gal | 5.71 gal |
| 1,500 sq ft | 4.29 gal | 8.57 gal |