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Paint Calculator
Estimate gallons or litres of paint for walls, minus doors and windows, for any number of coats.
How it works
Wall area = perimeter × height − 21 ft² per door − 15 ft² per window. Paint = wall area × coats ÷ coverage. Typical coverage is 350–400 ft² per gallon; check your can.
Examples
- 12 × 12 ft room, 8 ft walls, 1 door, 2 windows, 2 coats: 333 ft² × 2 ÷ 350 = 1.9 gal (7.2 L).
FAQ
Do I need primer?
Usually for new drywall, stains or big colour changes. Primer coverage is similar to paint.
Does this include the ceiling?
No; add ceiling area (length × width) separately.