If you enter a perimeter, length and width are ignored.
These results show the net exterior wall area after subtracting openings and the estimated paint volumes including your coats and waste allowance. Values are rounded and intended as planning estimates.
Quick guide (with a simple example)
This calculator turns exterior wall sizes into paint volume by combining area, coverage per coat, and allowances.
- Net wall area = gross wall area − openings (doors, windows, and other exclusions).
- Topcoat (per coat) = net area ÷ coverage (ft²/gal).
- Total topcoat = per-coat × coats × absorption × (1 + waste%).
- Primer uses the same idea with primer coverage and primer coats.
Worked example (US units)
Suppose your net paintable area is 2,400 ft², topcoat coverage is 350 ft²/gal, topcoat coats = 2, waste = 10%, absorption = 1.00. Then topcoat ≈ (2,400 ÷ 350) × 2 × 1.10 ≈ 15.1 gallons. Use the built-in can planner to pick practical can sizes.
Common pitfalls
- Rough or porous exteriors (stucco, bare wood, new cement board) often need more paint than label coverage.
- Spraying, masking, and windy conditions typically increase waste compared with careful rolling.
- If you paint multiple colors or accent areas, estimate them separately.
FAQ
How accurate are these exterior paint estimates?
Estimates use the wall area you enter, coverage presets, absorption multipliers, and your waste allowance. Real projects can vary with product formulation, spraying vs rolling, weather, and texture. Always size up if unsure and follow the product label.
What defaults are used for coverage and openings?
Defaults assume 400 ft²/gal for flat, 350 for eggshell/satin, 300 for semi-gloss, and 200 for primer with 10% waste. Door and window areas default to 21 and 12 ft² (1.8 m² and 1.2 m²). Override coverage or absorption if your paint line differs.
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