Exterior Paint Area & Quantity Calculator

How to use 1) Pick a mode: whole building, per facade, or direct area. 2) Enter wall sizes, then subtract doors/windows in “Openings”. 3) Adjust coats, waste, and primer, then review gallons and liters.

Unit system US (ft, ft², gal) Metric (m, m², L)

Building length (ft) Building width (ft) Wall height per story (ft) Stories Perimeter override (ft, optional)

If you enter a perimeter, length and width are ignored.

Openings (subtract from wall area)

Door and window areas start with common defaults (about 21 ft² for a door and 12 ft² for a window, or 1.8 m² and 1.2 m²). Adjust them if your sizes differ.

Doors (count) Windows (count) Other openings area Area per door Area per window

Paint settings

Finish Substrate Topcoat coats Waste allowance (%) Include primer Primer coats

Coverage overrides (optional)

Topcoat coverage (ft²/gal) Primer coverage (ft²/gal) Absorption factor

Leave blank to use presets; higher absorption reduces coverage.

Gross wall area 0.0 ft²

Openings area 0.0 ft²

Net paintable area 0.0 ft²

Topcoat needed 0.00 gal / 0.0 L

Primer needed 0.00 gal / 0.0 L

Total paint 0.00 gal / 0.0 L

Suggested cans (US) —

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.

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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