Exterior Paint Calculator
Estimate exterior wall paint from your home's footprint and wall height. It approximates wall area as the perimeter times height, less ~15% for doors and windows.
Exterior Paint calculator
How it's calculated: Wall area = 2 × (house length + width) × wall height, minus 15% for doors and windows; multiply by coats and divide by about 300 sq ft per gallon.
How to estimate exterior paint
- Exterior surfaces are rougher, so coverage is lower - plan on ~300 sq ft per gallon per coat.
- Two coats is normal for a color change or weathered siding. Prime bare wood first.
- This estimates field walls only; trim, soffits and accents are separate.
- Prep is the job: washing, scraping, sanding and spot-priming take longer than painting and decide how long the finish lasts.
- Paint in dry weather and follow the shade around the house - direct hot sun skins paint over before it levels.
Frequently asked questions
How much paint to cover a house exterior?
A single-story 40x30 home with 9 ft walls has roughly 1,260 sq ft of wall. Two coats need about 8-9 gallons after deductions.
How often does a house need repainting?
Wood siding commonly goes 5-10 years; fiber cement and stucco often longer. Sun-facing and weather-facing walls fail first, so inspect those to time the job.
Do I add gables to the estimate?
Yes - this calculator covers the main walls only. A gable is a triangle: half its width times its height. Add each gable's area to your total before figuring gallons.
Is it better to spray or roll exterior paint?
Spraying is much faster but loses paint to overspray and needs serious masking; brushing and rolling work paint into texture and waste less. Many pros spray then back-roll to get both speed and adhesion.
Can I get away with one coat?
Only when recoating a sound surface in a similar color. Color changes, chalky paint and bare or spot-primed areas need two coats to cover evenly and last.