Paint Coverage Calculator
Example: Total wall area: 900 sq ft · Number of coats: 2 coats · Coverage per gallon: 350 sq ft · Price per gallon: 45 $
| Gallons to buy | 6 |
| Exact gallons required | 5.14 |
| Total paint cost | $270 |
Worked example
Say you have 900 square feet of wall and want two coats. That is 1,800 square feet of painting. At the common 350 square feet per gallon, you need 1,800 / 350 = about 5.1 gallons, which rounds up to 6 gallons to buy. At $45 a gallon that is $270. Buying the whole 6 gallons rather than the exact 5.1 protects you against the color being impossible to re-match later.
Frequently asked questions
Why round up to whole gallons?
Paint is sold in whole gallons and quarts, and custom-tinted colors are hard to match exactly on a second trip, so it is safer to round up. The calculator shows both the exact requirement and the whole gallons to buy so you can decide whether to grab quarts for a small remainder.
What coverage number should I use?
Use the coverage printed on your specific paint, which commonly ranges from about 300 to 400 square feet per gallon for a single coat on a smooth, primed wall. Rough, porous, or unprimed surfaces cover less, so drop the number for textured drywall, bare wood, or masonry.
Do I really need two coats?
Most color changes and most flat-to-color jobs need two coats for an even, durable finish; a same-color refresh over a sound surface can sometimes get away with one. Priming a drastic color change first can reduce the number of finish coats you need.
How do I find my wall area?
Multiply the perimeter of the room by the ceiling height, then subtract large openings like doors and windows. For a rough estimate you can skip small deductions, since the waste from cutting in and touch-ups tends to absorb them.