Paint Calculator
Estimate gallons for a rectangular room. Coverage starts at 350 square feet per gallon, per coat, and you can replace it with the number on the can.
Use it before you buy paint, when you know the room size, the coats, and the coverage on the can.
How this calculator works · Paint estimate from your measurements
Compare scenarios
How we calculated this
Wall area is the perimeter times the height. Ceiling area is added when you include it. Door and window area is subtracted. Gallons are the paintable area times coats, divided by coverage, then rounded up to the next whole gallon.
What does this mean?
Buy 2 gallons. The exact amount is 1.78 gallons for 312 square feet.
Your assumptions
Edit assumptions- Room
- 12.0 × 10.0 ft
- Wall height
- 8.0 ft
- Coverage
- 350 sq ft / gallon / coat
- Ceiling
- Not included
This calculator provides an estimate for planning. Material yield, waste, prices, and local requirements may vary.
Embed
Paste this iframe to show the calculator on another page. Taller results scroll inside the frame.
<iframe src="https://myhousingiq.com/embed/paint-calculator" title="Paint Calculator" width="100%" height="900" style="border:0;max-width:1080px;"></iframe>
How the estimate is calculated
Wall area is the perimeter times the height. Ceiling area is optional. Doors and windows are subtracted.
Gallons are area times coats, divided by coverage, rounded up to the next whole gallon.
Gallons
Gallons to buy = ceiling of (paintable square feet × coats ÷ coverage per gallon).
Example
- Measure the room and the wall height.
- Subtract a rough door and window area. One door is about 20 square feet.
- Use two coats unless the can or the color change says otherwise.
With the numbers filled in on this page, the estimate is 2 gallons.
What changes the result
Texture and color
Rough walls and a large color change can need more paint than the can’s smooth-wall coverage.
Ceiling
Leave it off unless you are painting it the same product.
Trim
Trim is not included.
Questions
Why round up?
You cannot buy a fraction of the last gallon in this estimate, and running short mid-coat is the worse outcome.
What is a typical coverage?
About 350 square feet per gallon per coat is a common planning figure for smooth walls. The can is better.
Does this price the paint?
No. It estimates gallons. A shopping link appears only if a real partner is configured.