Paint Coverage Calculator — Gallons Needed by Area & Coats
Who this is for: For anyone standing in the paint aisle guessing between two gallons or three — and for painters who quote gallon counts to customers.
Wall area and coats in — get exact gallons, primer, and the buy list by can size.
Quick answer: Paint gallons = area × coats ÷ 350 sq ft/gal, rounded up. A 330 sq ft bedroom for two coats: 1.89 → buy 2 gallons. Primer (new drywall or dark-to-light) adds one coat's worth at the same rate. Enter your area below for the exact buy list.
Or use the room calculator
Type "yes" for one primer coat (new drywall, dark→light, stains)
| Coverage | 350 sq ft/gal/coat (planning number) |
|---|---|
| Formula | Gallons = area × coats ÷ coverage, round up |
| Primer | Same rate, one coat, when needed |
| Example | 330 sqft × 2 ÷ 350 = 1.89 → 2 gal |
| Touch-up | +1 can if within 10% of whole gallon |
| Status | Figures follow 2026 US industry averages: pro interior $2–6/sq ft of wall area, coverage 350–400 sq ft/gal per coat, paint $15–60/gal by tier, exterior $1.5–5/sq ft. Estimates for budgeting — your local market and surface condition move the final number. |
How many gallons of paint do I need?
One formula: area × coats ÷ coverage. A US gallon of interior paint covers 350–400 sq ft per coat (350 is the safe planning number — textured walls and deep color changes eat coverage). Round up to buyable gallons and add one if the math lands within 10% of a whole gallon, because touch-ups are certain. Primer follows the same formula at one coat — needed for new drywall, dark-to-light changes, and stain blocking. Example: 330 sq ft bedroom, two coats: 330 × 2 ÷ 350 = 1.89 → buy 2 gallons (or one 1-gal + one 5-gal bucket if the color is a keeper).
Common uses
- The paint-aisle decision: exactly how many cans to buy
- Checking a painter's gallon count against the math
- Budgeting primer for a dark-to-light repaint
- Planning 5-gal bucket vs 1-gal purchases for big jobs