Roof Paint Area & Quantity Calculator

Estimate paintable roof area plus topcoat and primer gallons or liters. Switch between building size with slope, plane-by-plane entry, or a known area, then subtract skylights and other exclusions and adjust coats, waste, and coverage.

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How to use 1) Pick a mode: building dimensions + slope, per-roof-plane, or known area. 2) Enter sizes, subtract skylights/fixtures, and set coats, waste, and primer. 3) Review paintable area and gallons/liters. Copy the URL to share the setup.
Unit system

Building footprint & slope

Include the eave overhang; shape factor lets you tweak hips or complex forms.

Length runs along the eaves; width runs along the ridge. Overhang adds both sides.

Exclusions (skylights, fixtures)

Subtract openings that will not be painted.

Paint settings

Pick finish, substrate, coats, waste, and primer. You can override coverage if needed.

Coverage overrides (optional)

Leave these fields blank to use the built-in coverage and absorption presets for typical roof coatings.

All calculations run in your browser; no data is sent to a server.

Frequently asked questions

How accurate are these roof paint estimates?

They are planning values only. Results combine your roof dimensions, slope factor, exclusions, coverage presets, absorption factor, coats, and waste allowance. Real projects vary with product formulation, weather, and surface condition. Always follow the paint label and size up if unsure.

Can I override coverage or primer settings?

Yes. Turn primer on or off, change coats, and override coverage or absorption values when your product differs from the built-in presets. The calculator ships with typical roof coating presets; if your product label lists different coverage, enter those numbers in the override fields.

Comments

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