Exterior House Paint Calculator
Exterior jobs are measured in wall square footage, not floor area. Measure each side: width × height to the eaves, plus gable triangles (½ × width × gable height). Add them up and enter the total.
Gallons by house wall area (2 coats, 350 sq ft/gal)
| Wall sq ft | Lap siding gal | Buy | Rough/stucco gal | Buy |
|---|---|---|---|---|
| 1,000 | 6.3 | 1 x 5-gal + 2 gal | 7.1 | 1 x 5-gal + 3 gal |
| 1,500 | 9.4 | 2 x 5-gal | 10.7 | 2 x 5-gal + 1 gal |
| 2,000 | 12.6 | 2 x 5-gal + 3 gal | 14.3 | 3 x 5-gal |
| 2,500 | 15.7 | 3 x 5-gal + 1 gal | 17.9 | 3 x 5-gal + 3 gal |
| 3,000 | 18.9 | 4 x 5-gal | 21.4 | 4 x 5-gal + 2 gal |
Quick way to estimate wall area
For a simple rectangular house: perimeter × wall height, plus gables. A 40 × 30 ft one-story ranch with 9 ft walls has 140 × 9 = 1,260 sq ft, plus two gables of about ½ × 30 × 6 = 90 sq ft each, for about 1,440 sq ft total. Subtract roughly 15–20 sq ft per window and 21 per door.
Exterior-specific tips
- Texture factors are rules of thumb. Rough surfaces hold more paint, and spraying wastes about 20–30% more than rolling.
- Trim, fascia and doors are usually a different color, so estimate them separately in linear feet (about 1 gal per 400 linear ft of 6 in trim).
- Paint between 50 and 90 °F, and keep out of direct midday sun when you can.
Frequently asked questions
How much exterior paint for a 2,000 sq ft house?
A 2,000 sq ft house (floor area) often has 1,800–2,400 sq ft of wall. At 2 coats on lap siding, that's roughly 11–15 gallons. Measure the walls for a real number.
How many square feet does a gallon of exterior paint cover?
About 300–400 sq ft per coat on smooth siding, and less on rough or porous surfaces.
Do I need primer on exterior siding?
Prime bare wood, patched areas and chalky surfaces. Sound, previously painted siding usually doesn't need a full prime coat.
Last reviewed October 2026 by Jim Frith. These are planning estimates; confirm quantities with your supplier and follow local codes.