Paint Calculator
Estimate paint for a room and what it'll cost. Enter the dimensions, choose whether to include the ceiling, set the coats, and add a price per gallon.
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Check it outCoverage, coats, and cost
A gallon covers roughly 350–400 sq ft per coat on smooth walls. Add the ceiling if you're painting it, count your coats (deep color changes and bare drywall need more), and set the price per gallon for a budget. Buy a little extra for touch-ups, since dye lots vary between cans.
How it’s calculated
Wall area = 2 × (length + width) × height, minus doors and windows, plus the ceiling if selected. Gallons = area × coats ÷ coverage per gallon.
Results update as you type and are estimates, not professional advice — verify important decisions with a qualified professional.
Worked example
A 12x12 room with 8-ft walls, 1 door and 2 windows, 2 coats needs ~1.9 gallons (buy 2).
Common mistakes
- Forgetting to subtract doors and windows, or to add the ceiling.
- Buying exactly the estimate with nothing for touch-ups.
Where it is used
- Budgeting paint and cost for a room repaint.
- Checking how much a color change (extra coat) adds.
Frequently asked questions
Does it include the ceiling?
Only if you choose 'Yes' — it then adds length × width to the paintable area.
How many coats should I plan?
Two is typical. Bare drywall, big color changes, or going light-over-dark may need a primer coat plus two finish coats.
Why round up to whole gallons?
Paint is sold by the gallon (or quart). Rounding up ensures you don't run out mid-wall and gives touch-up paint.
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