How Much Paint Do I Need for a House Exterior?
Measuring an exterior
Use the I already know the wall area mode in the paint calculator, because an exterior is not a box you can describe with a length and a width. Build the area up in pieces:
- Walls: perimeter of the house × wall height, per storey. A 40 × 30 ft house has a 140 ft perimeter; at 9 ft per storey that is 1,260 sq ft per storey.
- Gables: each gable triangle is ½ × width × height. A 30 ft wide gable rising 7 ft adds 105 sq ft.
- Dormers and bump-outs: measure and add as separate rectangles.
- Subtract openings: windows and doors, at their real sizes on an exterior — patio sliders and picture windows are far bigger than the 15 sq ft interior rule of thumb.
- Do not subtract soffits and fascia from the body figure; count them with the trim instead.
Coverage by siding type
| Surface | Sq ft per gallon | Notes |
|---|---|---|
| Smooth fibre cement, previously painted | 350–400 | Best case on an exterior |
| Vinyl siding | 300–350 | Must use a paint rated for vinyl; do not go darker than the original |
| Smooth wood or hardboard siding | 300–350 | |
| Textured fibre cement, lap with grain | 250–300 | Grain and edges eat material |
| Rough-sawn cedar, T&G, board and batten | 200–250 | Many edges; back-brushing essential if spraying |
| Stucco, block, brick | 150–250 | Porous; often needs a masonry primer or filler first |
Worked example
A single-storey 40 × 30 ft house with 9 ft walls, two gables 30 ft wide rising 7 ft, ten windows averaging 20 sq ft, two doors at 21 sq ft, textured lap siding, two coats:
- Walls: 140 ft perimeter × 9 ft = 1,260 sq ft
- Gables: 2 × (½ × 30 × 7) = 210 sq ft
- Openings: (10 × 20) + (2 × 21) = 242 → subtract
- Body area: 1,260 + 210 − 242 = 1,228 sq ft
- Two coats at 275 sq ft/gal: 1,228 × 2 ÷ 275 = 8.9 gallons
- Order 9 gallons of body colour — or two 5-gallon pails, which is usually cheaper per gallon and guarantees a single tint batch.
Trim, soffits and accents are a separate calculation
| Element | How to estimate |
|---|---|
| Fascia and rake boards | Linear feet × board width, converted to sq ft |
| Soffits | Linear feet × overhang depth |
| Window and door casings | Roughly 15–20 sq ft per average opening |
| Shutters, railings, columns | Measure individually; railings consume more than they look |
| Front door | About 21 sq ft per side |
Trim usually lands in the range of one to three gallons for a typical house, and it is worth buying a higher-grade product than the body since trim takes the weather and the handling.
Exterior-specific cautions
- Spraying loses material. Transfer efficiency drops with any breeze, and back-brushing is needed on rough or grained siding to work paint into the surface. Add 20–30% if spraying.
- Two coats, genuinely. Exterior films weather from day one, and a one-coat exterior job fails years earlier at every south-facing wall.
- Buy in one tint batch, ideally 5-gallon pails, and box partial cans together. Colour variation between batches shows badly across a long elevation in full sun.
- Watch the weather window. Most exterior paints want a surface and air temperature above roughly 50 °F and no rain or dew for several hours after application — check the can, since low-temperature formulations differ.
- Prime bare wood and stains, and expect masonry to need its own primer or filler.
Enter the room and get the paintable area, the gallons required and the exact combination of cans to buy — doors and windows subtracted, coats and spread rate under your control.
Frequently asked questions
How many gallons of paint for a 2,000 sq ft house?
Floor area is not the right input — what matters is wall area. A typical single-storey house of that size might have 1,300 to 1,700 square feet of body surface, which at two coats and 275 to 350 square feet per gallon works out to roughly 8 to 12 gallons plus trim.
How do I measure a house exterior for paint?
Multiply the perimeter by the wall height for each storey, add each gable as half base times height, add dormers separately, then subtract windows and doors at their actual sizes. Count soffits and fascia with the trim rather than the body.
Does spraying use more paint than rolling?
Yes, noticeably — overspray and drift mean lower transfer efficiency, and rough or grained siding also needs back-brushing to work the paint in. Budget 20 to 30 percent more material if you are spraying an exterior.
Can you paint vinyl siding?
Yes, with a paint specifically rated for vinyl, and you must not choose a colour significantly darker than the original. Darker colours absorb more heat than the siding was designed for and can warp it.
- How Much Does a Gallon of Paint Cover?
- How Many Coats of Paint Do You Need?
- How Much Primer Do I Need — and Do You Even Need It?
- Paint Sheen Guide: Flat, Eggshell, Satin, Semi-Gloss