Paint Calculator — Gallons Needed for Any Job
Nobody wants to climb back down mid-wall for another gallon — or buy three extra and eat the cost. This paint calculator tells you exactly how many gallons a job needs, including the coats.
Standard coverage is 350 sq ft per gallon per coat. Textured surfaces eat paint much faster, and the calculator's cost estimate helps you price the job, not just the paint.
Paint needed
3 gal
Rough cost (est.)
$135
Coverage
350 sq ft/gal
Standard coverage is 350 sq ft per gallon per coat. Textured surfaces drop to ~250. Add 10% for touch-ups.
The formula
Gallons = (Surface sq ft × Coats) ÷ Coverage per gallon (350 smooth / 250 textured). Budget ~$40–50 per gallon for decent contractor-grade paint.
Pro tips
- →Count every coat — primer counts too. Two coats of color plus primer is a three-coat job.
- →Drop the coverage to 250 sq ft/gal for stucco, brick, and heavily textured walls.
- →Add 10% for touch-ups and cut-ins. Leftover paint is cheaper than a second trip to the store.
Frequently Asked Questions
How many gallons to paint a 12×12 room?+
A 12×12 room with 8-ft ceilings has ~384 sq ft of wall. At 350 sq ft/gal with 2 coats: about 2.2 gallons — so 3 gallons.
How much paint for a 2,000 sq ft house exterior?+
Exterior walls around 1,600–2,400 sq ft of surface. At 350 sq ft/gal, 2 coats: 10–14 gallons plus primer.
Does primer count as a coat?+
Yes — and on bare drywall or stained surfaces it's the coat that matters most. Count it in your gallons.
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