Exterior Paint Calculator
Calculates exterior house paint requirements based on home perimeter, eave height, siding material texture (wood, stucco, fiber cement, vinyl), gable end areas, and door/window deductions.
Formula
Exterior Area = (Perimeter × Height) + (0.5 × Gable Width × Gable Height × Gables) - Openings
1. Rectangular Wall Area = Perimeter × Eave Height 2. Gable Peak Area = 0.5 × Gable Width × Gable Height × Number of Gables 3. Deductions = (Doors × 30 sq ft) + (Windows × 15 sq ft) 4. Net Area = Total Area - Deductions 5. Gallons = (Net Area × Coats × Waste) ÷ Siding Coverage Rate
Inputs
- Total House Perimeter
- Average Wall / Eave Height
- Gable Ends (Triangular peaks)
- Average Gable Base Width
- Gable Peak Height
- Siding Substrate
- Coats
- Exterior Doors & Garage Doors
- Exterior Windows
Worked example
A 2-story house with 140 ft perimeter, 18 ft wall height, two 30x8 ft gables, 12 windows, and 2 entry doors + 2 garage doors receiving 2 coats of exterior acrylic.
Outcome: Total gross surface equals 2,760 sq ft. Openings deduct 300 sq ft, giving 2,460 net sq ft. Two coats over smooth siding with 10% waste requires 15.4 gallons (round up to three 5-gallon pails plus 1 single gallon).
What is the best temperature to apply exterior paint?
Most modern 100% acrylic exterior paints can be applied between 50°F and 90°F (some specialized low-temp formulas down to 35°F), with relative humidity under 70% and no rain forecasted for 24 hours.
How much paint is lost to overspray when using an airless sprayer?
Airless sprayers typically lose 15% to 25% of material to overspray and atmospheric drift depending on wind conditions, tip size, and pressure settings.