A 1,500 sq ft floor plan does not translate directly into a paint quantity. For interiors, the useful number is paintable wall area after doors and windows, multiplied by coats, then divided by the coverage on the can. A typical whole-home project can easily land in the low-to-mid teens of gallons, but room layout, ceiling height, color change and coverage can move the answer substantially.
How to work it out
- Measure or estimate the perimeter of the rooms you are actually painting.
- Multiply perimeter by wall height to estimate wall area.
- Subtract meaningful door and window area.
- Multiply by the number of coats and add a waste/touch-up allowance.
- Divide by the manufacturer’s stated square-foot coverage per gallon and round purchase quantity up.
Example
If your combined paintable wall area is 3,900 sq ft, you plan two coats, add 10% for waste, and your paint covers 350 sq ft per gallon, the estimate is 24.5 gallons before rounding. The same 1,500 sq ft home with fewer partitions or one-coat repainting could need far less.
Floor area is only a rough proxy. Open-concept layouts, hallways, closets, stairwells, vaulted areas and textured walls all change the true wall area.
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