contractor · 2026-05-01
Calculate paint gallons and total project cost for an exterior repaint, accounting for coats, surface texture, and primer.
| Wall surface area (sqft) | 2,400 |
| Coverage (sqft per gallon) | 350 |
| Coats | 2 |
| Paint $ per gallon | $65 |
| Primer $ per gallon | $35 |
| Surface needing primer % | 30% |
| Labor $ per sqft | $2 |
| Prep + masking flat fee | $600 |
| Paint gallons needed | 13.7 |
| Primer gallons needed | 2.1 |
| Paint + primer cost | $963 |
| Labor cost | $4,200 |
| All-in $ per sqft | $2 |
The single biggest mistake on paint estimates is buying gallons by guess. Coverage rate × coats × wall area gives you a hard number. Buy 10% extra for touch-ups, but that's it.
One coat works only when (a) you're going same-color over a clean surface, (b) the existing paint is sound, and (c) you used premium 100% acrylic at full mil thickness. In real life, two coats hits the manufacturer's warrantied dry-film thickness and gives you the color depth you actually paid for.
Bare wood, chalking surfaces, color changes (especially dark→light), or any spots where you scraped down to bare substrate need primer. The shortcut: estimate 20-30% of surface for a repaint, 100% for new construction or a full color change.
Take perimeter × average wall height. For a typical 2-story, that's perimeter × 18-20 ft. Subtract ~20% for windows and doors. A 40×30 ft 2-story rectangle: (40+30)×2 × 18 × 0.8 = ~2,016 sqft.
Spray covers fast — 2-3× the rate of brush — but uses 25-40% more paint due to overspray. For rough surfaces (stucco, shake) sprayed + back-rolled is the only way to get full coverage. For smooth siding, brush + roller gives a thicker film and longer life.
Premium acrylic exteriors ($60-90/gal) carry 15-25 year warranties; contractor-grade ($25-40/gal) carries 5-7. The cost difference on a $5k paint job is $200-400 in product. The repaint cost difference is the entire $5k. Premium pays back unless you're flipping the house.
Because most of an exterior paint job isn't painting — it's prep. Pressure washing, scraping, caulking, masking windows and gutters, replacing rotten trim. A 'paint job' that skips those steps fails inside 3 years. Honest bids show prep separately.