The calculation, explained.
Wall area = 2 × (length + width) × height − openings, with ceiling area added only when selected. Paint = area × coats ÷ coverage × (1 + allowance/100). Whole one-gallon cans round up.
Review the example assumptions and results
- Room length
- 12 ft
- Room width
- 12 ft
- Wall height
- 8 ft
- Doors and windows
- 32 ft²
- Include ceiling (0 or 1)
- 0
- Coats
- 2
- Coverage per gallon
- 350 ft²
- Extra material
- 10 %
- Net surface area
- 352 ft²
- Paint required
- 2.2126 gal
- Buy one-gallon cans
- 3
How this tool works
Adjust the labeled inputs to see a new calculation. Units and assumptions are shown beside each field. Printed and copied results use the same calculation.
This is a planning estimate, not a structural design, permit document or binding quote. Check product specifications and actual site measurements.
A worked example for this tool
ConstructionHow Much Paint Do You Need for a 12 × 12 Room?
The paint estimate depends on wall height, openings, coats and coverage. A room size alone cannot tell you the correct purchase quantity.
Read the worked example ↗Keep going
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