Exterior Paint Calculator

Calculate how much exterior paint you need for your house. Enter wall length, height, doors, windows, and optional gable area to estimate gallons required with waste.

ft

Total length of the exterior wall (or sum of all sections).

ft

Eave height (ground to bottom of roof).

For reference only. If multiple sections have different heights, measure each separately and add the results.

Exterior doors (~3×7 ft = 21 sq ft each). Defaults to 1.

Exterior windows (~3×5 ft = 15 sq ft each). Defaults to 5.

sq ft

Optional: triangular gable area to add to wall area. Gable area = ½ × base × height.

Exterior paint typically needs 2 coats. Defaults to 2.

sq ft/gal

Square feet per gallon. Exterior paint typically covers 300-400 sq ft/gal.

%

Extra paint for overspray, spills, touch-ups. Defaults to 10%.

How this calculator works

This exterior paint calculator estimates paint for a single run of exterior wall. For complex houses with multiple wall heights, gables, or dormers, measure each exterior wall separately and add the results.

  1. Gross exterior area: wall length × wall height, plus any gable area you specify.
  2. Deductions: exterior doors (3×7 ft = 21 sq ft) and windows (3×5 ft = 15 sq ft) are subtracted.
  3. Paintable area: gross area − deductions.
  4. Total coverage requirement: paintable area × number of coats (default 2).
  5. Gallons: total coverage ÷ paint coverage rate (default 350 sq ft/gal), plus waste allowance (default 10%).

For rough-sawn siding, stucco, or brick, reduce effective coverage by 20-30% — these surfaces absorb significantly more paint than smooth primed surfaces.

Formula

wall_area       = wall_length × wall_height
gross_area      = wall_area + gable_area
door_area       = doors × 21 sq ft
window_area     = windows × 15 sq ft
paintable_area  = gross_area − door_area − window_area
total_paintable = paintable_area × coats
gallons         = total_paintable / coverage
recommended     = gallons × (1 + waste_pct / 100)
  rounded up to nearest quart (0.25 gal)

NOTE: For complex houses, measure each wall section separately
and sum the results.

Example

For a 100 ft exterior wall at 10 ft height, 1 door, 5 windows, 50 sq ft gable, 2 coats, 350 sq ft/gal, 10% waste:

  • wall_area = 100 × 10 = 1,000 sq ft
  • gross_area = 1,000 + 50 = 1,050 sq ft
  • door_area = 1 × 21 = 21 sq ft
  • window_area = 5 × 15 = 75 sq ft
  • paintable_area = 1,050 − 21 − 75 = 954 sq ft
  • total_paintable = 954 × 2 = 1,908 sq ft
  • gallons = 1,908 / 350 = 5.45 gallons
  • recommended = 5.45 × 1.10 = 6.0 → 6 gallons

Important assumptions

  • Standard exterior door: 3 × 7 ft = 21 sq ft.
  • Standard window: 3 × 5 ft = 15 sq ft.
  • Default coverage: 350 sq ft/gallon for exterior acrylic latex over a primed, smooth surface.
  • For rough-sawn siding, stucco, brick, or textured surfaces: reduce coverage by 20-30% (enter ~250-280 sq ft/gal).
  • Gable area (optional) = ½ × base × height of the triangle.
  • For multi-section houses: calculate each wall separately and sum — do NOT enter an average height.
  • This calculator estimates paint for walls only. Trim, fascia, soffits, and doors are calculated separately.

FAQ

How much exterior paint do I need for a 2,000 sq ft house?
A 2,000 sq ft single-story house has roughly 1,600-2,000 sq ft of exterior wall area (after subtracting openings). With 2 coats at 350 sq ft/gal, you'll need 9-12 gallons of paint. For a 2-story house, exterior wall area is typically 2,500-3,500 sq ft.
How do I calculate gable area?
Gable area = ½ × base × height. For a gable that's 20 ft wide at the base and 5 ft tall at the peak: ½ × 20 × 5 = 50 sq ft. Enter this in the optional gable field.
Does exterior paint cover the same as interior?
Exterior paint typically covers 300-400 sq ft/gal on smooth primed surfaces — similar to interior. However, rough surfaces (stucco, brick, rough-sawn siding) absorb more paint, reducing effective coverage to 200-280 sq ft/gal.
How many coats of exterior paint do I need?
Most exterior paints need 2 coats for full coverage and warranty compliance. Some premium paints advertise 1-coat coverage, but 2 coats are still recommended for durability and color retention.
Should I pressure-wash before painting?
Yes — pressure-washing removes dirt, mildew, and loose paint. Allow 24-48 hours of drying time before painting. Painting over a wet surface will cause peeling.