Exterior paint · US units

Exterior Paint Calculator — Gallons and Cost

Coverage is per coat. Default 250 sq ft/gal is Behr exterior’s published low end (250–400 for one coat) — not the interior PaintCare 350 fallback, and not an EPA number. Openings are the same Behr how-to 20 / 15 sq ft used indoors.

Basket 2026-08-27

Wall run and coats

Buy this month

3 gal

2.376 gal exact · 270 sq ft net · 2 coats

$140.94

Gross wall run: 320 sq ft
Doors + windows: −50 sq ft
Film (area × coats): 540 sq ft
After 10% convention: 594 sq ft

250 sq ft/gal is per coat. Two coats is twice the film. Pre-1978 paint disturbance is an EPA RRP question — this tool only points at the rule; it does not certify a job.

What calculator.net does not show

Interior tools default to 350. Exterior how-to copy at Behr still lists 250–400 sq ft per gallon for one coat. This page starts at 250, keeps two coats as the system recommendation, and prices Behr Premium Plus exterior satin 905001 at $46.98 from the 2026-08-27 basket. It is a wall-run takeoff (length × height), not a four-wall room.

Worked US example: 40×8 wall

8 ft height, 1 average door, 2 average windows, two coats, 250 sq ft/gal, 10% convention.

Gross wall = 40 × 8 = 320 sq ft
Openings    = 20 + 15 + 15 = 50 sq ft   (Behr how-to)
Net         = 320 − 50 = 270 sq ft
Film        = 270 × 2 coats = 540 sq ft
With 10%    = 540 × 1.10 = 594 sq ft
Exact gal   = 594 ÷ 250 = 2.376 gal → buy 3 gal
Cost @ $46.98 Behr Premium Plus exterior satin 905001
            = 3 × $46.98 = $140.94

EPA’s Renovation, Repair and Painting (RRP) rule is about lead-safe work in pre-1978 housing, not coverage. This calculator does not certify a job, issue a pamphlet, or decide whether you need a certified renovator. If the house is pre-1978 and you will disturb paint, read the EPA RRP page.

Citations

Behr. How Much Paint Do I Need? (exterior). Accessed 2026-08-27. https://www.behr.com/how-to/exterior/how-much-exterior-paint-to-buy — One gallon of any BEHR paint covers 250–400 sq ft in one coat. Same 15 / 20 sq ft opening allowances. Factor a second coat if necessary. Default coverage on the exterior paint calculator is the 250 low end, not the interior 350 fallback.
Behr. How Much Interior Paint to Buy for your Home. Accessed 2026-08-27. https://www.behr.com/consumer/how-to/interior/determine-how-much-interior-paint-to-buy — Average window about 15 sq ft; average door about 20 sq ft. How-to copy discusses one coat coverage; Behr system recommendation is two coats for most color changes and new work.
PaintCare. Buy the Right Amount of Paint to Reduce Waste. Accessed 2026-08-27. https://www.paintcare.org/buy-right/ — If the can does not list coverage, PaintCare says use 350 sq ft per gallon as a rough estimate. Coverage on cans is typically 300–400 sq ft/gal. This is the site default fallback — not an EPA figure.
US EPA. Lead Renovation, Repair and Painting Program. Accessed 2026-08-27. https://www.epa.gov/lead/lead-renovation-repair-and-painting-program — Pointer only. RRP is about lead-safe work in pre-1978 housing and child-occupied facilities, not paint coverage. This site does not certify renovators, issue the Renovate Right pamphlet, or decide whether a job is in scope.

These calculators estimate material takeoff for planning. They are not engineering, structural, or code advice. Confirm spans, mixes, fastener schedules, and permits with a licensed professional and the manufacturer’s current data sheet. Local shelf prices and tax are not this index.