WeekendCalc

Exterior House Paint Calculator

Enter the size of the house, how many storeys, and the siding. You get the area to paint, and the gallons and five-gallon pails to buy.

Your project

A typical window is 15 ft², a door 21 ft², and a 2-car garage door about 112 ft².

Results

Paint needed
7.4 gallons
Buy 1 five-gallon pail + 3 gallons
Surface to paint
1,290 ft²
Walls (before openings)
1,260 ft²
Gable ends
180 ft²
  • Trim, soffits, fascia, shutters and doors are not included: allow a few gallons for them, and buy trim paint separately. Primer is extra on bare or heavily weathered siding. Rough surfaces soak up much more paint, so choose the lower coverage figure.

How this calculator works

Add up the wall area (the perimeter × the height × the number of storeys) and the triangular gable ends, then subtract the windows and doors. Multiply by the number of coats and divide by the coverage per gallon, which depends on how rough the surface is.

gallons = (2 × (length + width) × height × storeys + gables × ½ × width × peak height − openings) × coats ÷ coverage

Worked example: a 40 × 30 ft single-storey house with 9 ft walls has 1,260 ft² of wall. Two gable ends 6 ft high add 180 ft², and 150 ft² of openings come off, leaving 1,290 ft². Two coats at 350 ft² per gallon needs 7.4 gallons: one five-gallon pail plus three gallons.

Tips before you buy

  • Wash the house, scrape and sand loose paint, patch and caulk, and prime bare wood before painting. Preparation decides how long it lasts.
  • Paint on a dry day when temperatures are in the range on the can, usually 50 to 90 °F, and out of direct hot sun.
  • Buy your paint in one batch and mix pails together (boxing) so the colour is consistent around the house.
  • Work out the siding area carefully for stucco and brick: they soak up a lot of paint, and may need a masonry primer.
  • Houses built before 1978 may have lead paint. Test before sanding or scraping, and follow lead-safe practices.

Tools & materials for this project

As an Amazon Associate we earn from qualifying purchases. These links do not change what you pay.

Exterior paint (5 gal)Exterior primerPaint sprayerPressure washerExterior caulk

Frequently asked questions

How much paint to paint the outside of a house?

A typical 1,500 to 2,000 ft² house takes 10 to 15 gallons for two coats. The calculator works out your own area, siding and coats.

How many gallons to paint a 2,000 square foot house?

It depends on the shape and the number of storeys, not just the floor area. A rough guide is about 1 gallon per 350 ft² of wall per coat, so a typical two-storey house of 2,000 ft² needs 12 to 16 gallons for two coats.

Do I need to include the trim?

Trim is usually painted in a different colour or sheen. Allow a few gallons for trim, soffits and fascia, and buy it separately.

Related calculators & guides

Paint CalculatorGallons of paint for a room, with coats, doors and windows.Deck Stain CalculatorGallons of deck stain or sealer for a deck and railings.Square Footage CalculatorArea of a rectangle, triangle, circle, trapezoid or ellipse.How Much Paint Do I Need? Room-by-Room GuideGuide

Estimates only. Results assume standard materials and simple shapes. Supplier products vary, and the final call on quantity, structure and safety is yours. Check your local code and your supplier's guidance before ordering.