How Much Paint for a House Exterior?

Updated 2026-07-19

Exterior paint is the biggest paint job most homeowners ever price out, and quotes swing wildly — one painter says 12 gallons, another says 20, and both might be honest. Exterior coverage depends on your siding material more than any other variable, so the only way to sanity-check an estimate is to run the math yourself.

The process is the same as interior work — area, openings, coverage, coats — but the coverage rates are lower, the surfaces are rougher, and the trim list is longer. Here is the full method on a real example.

Step 1: Measure the wall area

Walk the house with a long tape and add up the perimeter. A 30 × 50 one-story ranch has 160 linear feet of wall. Multiply by wall height — figure 9 feet for a single story (8-foot ceiling plus a foot of band joist) — and you get 1,440 square feet.

Gable ends add more: a gable 30 feet wide with a 4-foot rise is 60 square feet (half of base times height), and two of them add 120. Gross wall area for our example: about 1,560 square feet. Two-story house? Measure each story separately — a 2,500-square-foot two-story commonly pencils out to 2,800 to 3,500 square feet of wall after openings.

Step 2: Subtract doors and windows

Exterior openings are bigger and more numerous than interior ones. Use the same deductions — 15 square feet per window, 21 per door. Our ranch with 15 windows and 3 doors gives up 225 + 63 = 288 square feet, leaving roughly 1,270 square feet of paintable siding.

Painting the garage door to match the body color? Leave it in the total. Leaving the brick or stone veneer alone? Subtract that whole section of wall instead.

Step 3: Coverage depends on your siding

Spraying uses more paint than brushing and rolling — figure 10 to 15% extra — because a slice of every pass sails past the wall. Pros account for it in the bid; DIYers renting a sprayer should too.

1. Vinyl, aluminum, or previously painted fiber cement: 350–400 sq ft per gallon.
2. Painted wood siding or T1-11 in decent shape: 300–350 sq ft per gallon.
3. Stucco and brick: 200–300 sq ft per gallon — rough stucco can go lower.
4. Rough-sawn cedar, shakes, or weathered bare wood: 150–250 sq ft per gallon, and the first coat drinks it.

Step 4: Run the two-coat math

Exterior jobs are almost always two coats — sun and weather punish a thin film. Our ranch needs 1,270 × 2 = 2,540 square feet of coverage. On smooth fiber cement at 375 per gallon that is about 6.8 gallons, so buy 7. On rough cedar at 200 per gallon, the same house drinks nearly 13. That spread is why your neighbor's gallon count is useless for your house.

Trim is separate: fascia, soffits, corner boards, and window trim on a one-story ranch typically take 2 to 3 gallons for two coats, plus a gallon of accent color if the front door and shutters get their own.

Primer, weather, and other reality checks

Bare wood, spots scraped to bare substrate, and tannin-bleeding cedar all need primer — spot-prime at 300 to 400 square feet per gallon, or prime the whole house if more than a quarter of it is bare. Masonry going from unpainted to painted wants a masonry primer first.

Check the label's weather window before you schedule: most exterior paints want 50 to 90 degrees, no rain in the forecast, and time to dry before the overnight dew. A gallon count means nothing if you wash coat one off the siding.

Before you sign a painting contract or load up at the paint desk, run your own square footage and siding type through the paint calculator — walking into the conversation knowing your real gallon count is the best leverage you have.