How Many Gallons of Paint Do I Need per Square Foot (Exterior)?
At a typical 350 sq ft per gallon, one coat over 1,000 square feet needs about 3 gallons (1,000 ÷ 350 = 2.86 → 3). Rough surfaces drink more paint: stucco covers around 250 sq ft per gallon and brick about 200. Multiply by your number of coats — two coats is standard outdoors.
Key Takeaways
- Smooth siding: ~350 sq ft per gallon → 3 gal per 1,000 sq ft per coat.
- Rough stucco: ~250 sq ft per gallon → 4 gal per 1,000 sq ft per coat.
- Brick/masonry: ~200 sq ft per gallon → 5 gal per 1,000 sq ft per coat.
- Formula: gallons = area ÷ coverage × coats.
- Two coats is the standard for exterior durability.
How to Calculate Exterior Paint Gallons
Exterior math is simpler than interior: measure the wall area, pick the coverage rate for your surface, divide, then multiply by coats.
- 1Measure each wall: height × length, then add the walls together.
- 2Subtract large openings (garage doors, big windows) — or keep them as waste allowance.
- 3Pick your coverage: 350 (smooth siding), 250 (stucco), 200 (brick).
- 4Divide: area ÷ coverage = gallons for one coat.
- 5Multiply by coats (usually 2) and round up to whole gallons.
The Exterior Paint Formula
Coverage rates are printed on the can as a range — use the low end for weathered or previously unpainted surfaces.
Gallons = Wall area (sq ft) ÷ Coverage (sq ft/gal) × CoatsWorked Example: 1,500 Sq Ft, Two Coats
Full math for 1,500 sq ft of smooth siding at 350 sq ft per gallon, plus a surface coverage chart.
Wall area: 1,500 sq ft of smooth siding.
One coat: 1,500 ÷ 350 = 4.29 gallons.
Two coats: 4.29 × 2 = 8.57 → 9 gallons.
Buy 9 gallons — paint stores cannot sell you 0.57 of a gallon.
Same house in stucco: 1,500 ÷ 250 × 2 = 12 gallons.
| Surface | Coverage per gallon | Gallons per 1,000 sq ft (1 coat) |
|---|---|---|
| Smooth siding | 350 sq ft | 3 |
| Rough stucco | 250 sq ft | 4 |
| Brick / masonry | 200 sq ft | 5 |
Common Mistakes
- Using interior coverage rates outdoors — sun and texture change everything.
- Painting over bare wood or masonry with no primer and watching it soak in.
- Skipping the second coat to save money, then repainting two years sooner.
- Forgetting soffits, fascia, and trim in the area estimate.
- Buying exact gallons with nothing left for touch-ups.
Practical Tips
- Pressure-wash and let siding dry fully before painting.
- Paint in the shade — direct sun dries paint too fast and hurts adhesion.
- Box (mix) multiple gallons together for consistent color.
- Save one labeled can per color for future touch-ups.
- Run your measurements through the NOVORY Paint Calculator.
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