How Much Exterior Paint Do I Need? (Gallons for House Siding)
Quick answer: one gallon of exterior latex paint covers about 350–400 square feet of siding per coat. A typical 2,000 sq ft house needs about 5–6 gallons for two coats, plus 1–2 gallons for trim and doors. Here's how to measure your siding and get the exact count.
Step 1: measure the siding area
Exterior paint is sold by the gallon and coverage is in square feet per gallon, so the whole job is one area calculation. Measure the perimeter of the house (the length of every exterior wall added together) and multiply by the average wall height. A 40×30 ft single-story home has a perimeter of 140 ft; at an 8 ft wall height that's 1,120 sq ft of siding before you subtract openings.
Use the square footage calculator for each wall face, then add them. For a two-story house, do each level separately — the second story rarely has the same wall area as the first.
- Exterior paint chart by house size
- The siding-area formula, worked out
- Coverage on smooth vs textured siding
- Siding vs trim vs doors
- Priming and coats
- Common mistakes
Exterior paint chart by house size
These assume smooth siding, 8-ft walls, two coats on the siding, and exclude trim. Add ~10% for touch-ups.
| House size | Approx. siding area | Siding paint (2 coats) | + Trim & doors |
|---|---|---|---|
| 1,200 sq ft ranch | ~1,400 sq ft | 3–4 gal | +1 gal |
| 1,800 sq ft | ~1,900 sq ft | 4–5 gal | +1 gal |
| 2,000 sq ft | ~2,100 sq ft | 5–6 gal | +1–2 gal |
| 2,500 sq ft | ~2,600 sq ft | 6–7 gal | +1–2 gal |
| 3,000 sq ft | ~3,200 sq ft | 8–9 gal | +2 gal |
The siding-area formula, explained
The math is identical to interior paint but on a bigger scale:
Siding area − windows − doors ÷ coverage per gallon × coats = gallons you need
Worked example — a 1,800 sq ft house with 1,900 sq ft of siding:
- Minus 12 windows (12 × 15 = 180 sq ft) and 2 doors (42 sq ft) = 1,678 sq ft
- At 375 sq ft per gallon = 4.5 gallons per coat
- Two coats = 9 gallons → buy 9–10 gallons for the siding
Siding vs trim vs doors
Treat these as three separate quantities. The siding is the big surface area above. Trim and fascia are measured by linear foot — soffits, window and door casings, and corner boards add up fast, usually 1–2 gallons. Doors are each about 21 sq ft per face and often a contrasting color. When you're buying, count siding, trim and doors separately so you don't over-buy one and run short on another.
Priming and coats
Bare wood, new siding and stained or patched surfaces need a primer coat first — figure it over the full siding area, then two topcoats. Repainting an existing coat of the same color can often get away with two coats without primer. Coverage drops on texture: stucco, wood shingle and rough siding absorb more, so use ~250–300 sq ft per gallon there. Always round up — exterior paint is bought by the gallon and leftover is your touch-up supply.
Common mistakes
- Measuring by floor area, not siding area. Walls are bigger than the floor plan; you need the perimeter × height, not the sq ft of the footprint.
- Forgetting the second coat. Exterior paint takes two coats for even color and UV protection.
- Ignoring texture. Stucco and wood shingle drink more — cut coverage to ~250–300 sq ft per gallon.
- Not separating trim. Trim, soffits and doors are a separate 1–2 gallons people forget.
- Rounding down. Buy whole gallons and keep the extra; color matching a second trip never matches perfectly.