Paint Calculator
Calculate how many gallons of paint needed for any room.
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How It Works
Calculates gallons needed: wall area = 2x(length+width)x height. Each gallon covers ~400 sq ft per coat. Subtract doors (~20 sq ft) and windows (~15 sq ft each).
Formula
Gallons = Wall Area / 400Quick Reference
Common calculations — results you can verify instantly.
12×15 room, 8ft ceiling
432 sq ft walls / 400
~2.2 gallons (2 coats)
One 5-gal bucket covers
At 400 sq ft/gal
~2,000 sq ft per coat
Ceiling 12×15ft
180 sq ft / 400
~0.5 gallon per coat
Tips & Shortcuts
1 gallon covers ~350-400 sq ft per coat.
Dark to light color change needs 3 coats.
Common Mistakes
Not subtracting doors and windows
Subtract ~20 sq ft per door and 15 sq ft per window.
Buying for one coat when two needed
Most paint jobs require 2 coats. Calculate total.
Frequently Asked Questions
2(12+15)x8=432 sq ft. For 2 coats: ~2.2 gallons.
Flat: ceilings. Eggshell: living rooms. Satin: kitchens/baths. Semi-gloss: trim.
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