How to use this paint calculator
Enter room dimensions, openings, coats and product coverage to estimate paintable wall area and gallons.
How the calculation works
Wall area = 2 × (length + width) × heightPaintable area = wall area − openingsGallons = paintable area × coats ÷ coverageAdvertisementGoogle AdSense placeholder
Example project
A 12 × 14 ft room with 9 ft walls, one door, two windows and two coats needs roughly 3 gallons at 350 sq ft per gallon.
Practical tips
- Use the coverage printed on your paint can.
- Textured or porous walls can use more paint.
- Round up enough for touch-ups.
Frequently asked questions
How much does one gallon cover?
Many interior paints list around 350–400 sq ft per gallon; use your product label.
Should I subtract openings?
Large doors and windows can be subtracted for a tighter estimate.
Why round up?
Paint is sold in fixed container sizes and running short is inconvenient.