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Paint calculator
Gallons for a paint job from area, coats, and your paint's coverage rating.
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How it’s computed
Gallons = ceil(area × coats ÷ coverage per gallon). Defaults: 2 coats, 350 sqft/gal — a typical label rating; use the number on your can.
Decimal-exact and deterministic: identical inputs always return identical results. This is the same math Ask Donnie’s estimating engine runs — not an approximation, and never a language model doing arithmetic.
Common questions
Do I count primer?
Figure primer as its own pass — run the calculator again with coats = 1 and the primer's coverage rating.
Rough or porous surfaces?
Coverage drops on texture, masonry, and raw wood — the label usually gives a lower rating for rough surfaces. Enter that lower coverage number.
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