Exterior Paint Calculator
Exterior walls: enter the house footprint and the wall height (8–9 ft per storey, add gable triangles roughly as an extra 2–3 ft on the height). Lap siding and stucco have 10–20% more surface than the flat area, so the extra is set to 10%. Ceiling stays off.
Order 16 gallons (4 five-gallon pails) — one gallon covers 350–400 ft² per coat; buy a 5-gallon pail above 4 gallons — it is cheaper and one batch.
- Wall area
- 5,040 ft²
- Waste / cuts 10%
- + 504 ft²
- Coverage to buy
- 5,544 ft²
- Metric
- 468.2 m²
- Gallons (350 ft² each)
- 16
- Quarts (87 ft² each)
- 64
- Five-gallon pails5 gallons each
- 4
- Materials + delivery$25–$70 / gallon · Sep 2026
- $400 – $1,120
- Installed (with labor)typ. $6,940
- $4,180 – $11,200
Quantities follow the ticket. Links may earn us a commission at no cost to you; they never change a number.
What will this paint job cost?
See the installed price range for these quantities and get up to 3 quotes from local contractors. Free, no obligation.
How to calculate paint by hand
Gallons = [2 × (L + W) × H (+ L × W ceiling)] × coats × (1 + extra) ÷ 350
Worked example
- Wall area: 2 × (12 + 12) × 8 = 384 ft².
- Two coats: 768 ft²; plus 5% for touch-ups = 806 ft².
- Gallons: 806 ÷ 350 = 2.3 → 3 gallons (or 2 gallons + 2 quarts).
- With the ceiling (144 ft² × 2 coats = 288 ft²): 1,094 ft² → 4 gallons — buy a 5-gallon pail.
- 1 gallon, smooth primed wall
- 350–400 ft² per coat
- 1 gallon, textured or bare
- 250–300 ft²
- 12 × 12 room, walls, 2 coats
- ≈ 2–3 gallons
- Trim & doors, average room
- ≈ 1 quart per coat
Questions crews ask
How much paint for the outside of a house?
A 40 × 30 ft two-storey house has about 2,500 ft² of siding: at two coats and 10% extra that is 5,500 ft² → 16 gallons, or three 5-gallon pails plus one. Trim usually adds 2–3 gallons.
How many coats for exterior paint?
Two on bare or weathered siding after a primer coat; one coat can refresh sound paint in the same colour. Stucco and rough-sawn wood soak up the first coat and cover 200–250 ft² per gallon.
How do I estimate gable area?
Each gable end is a triangle: width × rise ÷ 2. A 30 ft wide gable with a 6/12 pitch rises 7.5 ft: 112 ft² per gable. Easier: add 2–3 ft to the wall height on the calculator and let it average out.