Exterior Paint Calculator
Estimate how much exterior paint your house needs — wall gallons by siding type and coats, plus primer and trim/door paint — with U.S. pricing, a coats comparison, and a downloadable PDF shopping list.
Coverage depends heavily on siding texture, porosity, and color change. Rough surfaces drink paint. Estimates use 2024-2025 U.S. prices. For planning purposes only.
| Coats | Wall Area | Wall Gallons | Wall Paint Cost |
|---|
For your 1,500 sq ft of wall at 350 sq ft/gal, $45/gal.
How to use the exterior paint calculator
Four quick steps turn your house size into a full paint order — body gallons for the walls and gables, trim, primer, and supplies — with doors and windows subtracted, U.S. pricing, a surface comparison, and a downloadable PDF.
Enter the house
Wall length, width, and height (or total wall area); add gable ends and subtract doors and windows.
Pick surface & coats
Choose siding, stucco, or masonry and 1–2 coats — the coverage per gallon updates to match.
Add trim, grade & extras
Add trim area, pick a paint grade, set the waste %, and add primer, supplies, or a labor rate.
Read results & save a PDF
Get body and trim gallons, a full cost breakdown, a surface comparison, and a material list.
How the exterior estimate is calculated
It starts from your wall area, adds the gable ends on peaked walls, and subtracts the doors and windows you’ll skip. Then it multiplies by coats, divides by the surface’s coverage, and rounds up to whole gallons — keeping body and trim separate. Here is the exact math.
Worked example — a one-story 40 ft × 30 ft house, 10 ft walls, 2 gables, lap siding
Walls: 2 × (40 + 30) × 10 = 1,400 sq ft
Gables (2): 2 × (½ × 30 × 6) = 180 sq ft
Openings: (2 × 21) + (10 × 15) = 192 sq ft → Net: 1,400 + 180 − 192 = 1,388 sq ft
Body gallons (2 coats, 350, +10%): (1,388 × 2 ÷ 350) × 1.10 ≈ 8.7 → 9 gal
≈ 9 gallons of body paint for 2 coats on lap siding, about $495 at $55 / gallon — plus trim and any primer.
Exterior paint estimating charts
Handy lookups for the questions people ask most — how surface texture changes coverage, gallons by house size, and typical U.S. costs. Figures use the calculator’s defaults (2 coats, +10% waste), so always confirm your own can’s coverage.
| Exterior surface | Coverage / gallon | Notes |
|---|---|---|
| Smooth / vinyl siding | ~400 sq ft | Flat and sealed; best coverage |
| Wood lap / clapboard | ~350 sq ft | Grain and laps take a little more |
| Rough-sawn / shakes | ~275 sq ft | Open texture soaks up paint |
| Stucco | ~250 sq ft | Deep profile; more surface than it looks |
| Brick / masonry | ~200 sq ft | Porous; the thirstiest surface |
Texture matters more outdoors than in. A rough or porous wall has far more real area than its flat measurement, so it can need up to twice the paint of smooth siding over the same dimensions.
| Footprint | Perimeter | Wall area | Gallons (2 coats) |
|---|---|---|---|
| 30 × 20 | 100 ft | 1,000 sq ft | 7 gal |
| 40 × 30 | 140 ft | 1,400 sq ft | 9 gal |
| 50 × 30 | 160 ft | 1,600 sq ft | 11 gal |
| 50 × 40 | 180 ft | 1,800 sq ft | 12 gal |
| 60 × 40 | 200 ft | 2,000 sq ft | 13 gal |
Walls only, at 350 sq ft/gallon. Add gable ends and subtract openings for your home. A two-story house roughly doubles the wall height, and so the gallons.
| Wall area | Smooth (400) | Lap (350) | Stucco (250) | Brick (200) |
|---|---|---|---|---|
| 800 sq ft | 5 gal | 6 gal | 8 gal | 9 gal |
| 1,200 sq ft | 7 gal | 8 gal | 11 gal | 14 gal |
| 1,600 sq ft | 9 gal | 11 gal | 15 gal | 18 gal |
| 2,000 sq ft | 11 gal | 13 gal | 18 gal | 22 gal |
| 2,800 sq ft | 16 gal | 18 gal | 25 gal | 31 gal |
Gallons = (wall area × 2 ÷ coverage) × 1.10, rounded up. Brick and stucco can need roughly double the paint of smooth siding for the identical wall — set your surface so the estimate is right.
| Grade | Typical U.S. price | Best for |
|---|---|---|
| Budget exterior | $30–$45 / gallon | Sheds, quick refreshes; may fade sooner |
| Standard exterior | $45–$60 / gallon | Most homes; solid 2-coat durability |
| Premium (paint + primer) | $60–$90 / gallon | Best fade, mildew & weather resistance |
| Exterior primer | ~$35 / gallon | Bare wood, masonry, big color changes |
| Supplies | ~$60–$150 / job | Rollers, brushes, tape, drop cloths, ladder |
2024–2025 U.S. ballparks matching the calculator’s defaults. Exterior paint costs more than interior but premium grades resist weather and fading for years longer, so cost per year often favors the better paint. Your local prices will vary.
perimeter × height
add for peaks
separate / subtract
Exterior paint covers the body of the house, with the gables added and the openings taken out. Trim usually gets its own color, so it’s counted on its own.
- Walls — perimeter times wall height: 2 × (L + W) × H, the bulk of the body.
- Gable ends — each peaked wall adds about ½ × width × rise; easy to forget, so add it in.
- Trim & openings — subtract doors and windows; estimate fascia, soffits, and corners separately.
Everything the calculator works out
One set of house dimensions gives you a complete exterior order — body and trim gallons, primer, supplies, and a costed surface comparison.
Key figures every exterior job depends on
Built for any exterior job
From a single wall or a shed to a full two-story repaint, the same calculator scales to the house, the surface, and the coats.
Repainting the house or a shed and wants to buy the right gallons and pick the good weather window.
- Set the surface to match your siding
- Don’t forget the gable ends
- Paint in dry, mild weather
Bidding exteriors and needs body, trim, primer, supplies, and labor per square foot in one place.
- Split body and trim colors cleanly
- Add a labor rate for a full bid
- Save the PDF material list for the quote
Refreshing rentals or a flip and comparing budget versus premium paint on total cost and longevity.
- Compare grades on cost per gallon
- Prime bare and repaired areas
- Total gallons across the whole exterior
7 tips for an accurate exterior paint order
Small habits keep your count right and your finish even, weather-tight, and long-lasting.
Exterior paint calculator FAQ
The gallons, coverage, surface, and U.S. cost questions people ask most before painting a house exterior.
Work out the wall area as the perimeter times the wall height, add the gable ends on peaked walls, then subtract about 21 sq ft per door and 15 sq ft per window. Multiply that net area by the number of coats and divide by the paint’s coverage.
A one-story 40 × 30 ft house with 10 ft walls, two gables, two doors, and ten windows has about 1,388 sq ft of paintable body. At two coats on lap siding (about 350 sq ft per gallon), that’s roughly 9 gallons.
On smooth or vinyl siding, a gallon of exterior paint covers about 400 sq ft per coat. Rougher and more porous surfaces cover much less.
Rough guides per gallon: wood lap siding about 350 sq ft, rough-sawn or shakes about 275, stucco about 250, and brick or masonry closer to 200 sq ft. The rougher the wall, the more paint it drinks.
Yes, more than almost anything else. A textured or porous surface has far more actual area than its flat measurement, so it soaks up more paint.
The same house that needs about 8 gallons on smooth siding can need around 16 gallons on brick — double the paint for the identical wall area. Always set the surface type so the coverage matches your home.
Include the gable ends on any peaked walls — each gable adds roughly half its width times its rise in square feet, which is easy to forget and can leave you short.
Trim like fascia, soffits, corner boards, and window casings is usually painted in a second color, so estimate it separately. The calculator keeps body and trim apart so each color is ordered on its own.
Two coats is the standard for exterior work and gives the durability and even color that hold up to weather and sun. One coat may refresh same-color siding with premium paint.
Plan on priming plus two coats for bare wood, big color changes, or fading a dark color to a light one. Each coat multiplies the paint you need, so coats drive the total as much as house size.
Prime bare wood, new siding, patched or repaired areas, stains, and bare masonry so the topcoat bonds well and colors stay even. Bare and weathered wood in particular should always be primed.
Over sound, previously painted siding in a similar color you can often skip separate primer, especially with a self-priming exterior paint. Primer goes on as one coat and covers a bit less than paint.
In the U.S., exterior paint runs more than interior: budget grades about $30 to $45 per gallon, standard about $45 to $60, and premium exterior paint-and-primer roughly $60 to $90.
Premium exterior paint costs more but resists fading, mildew, and weather far better and can last years longer, so it often wins on cost per year. Add primer, supplies, and labor if you hire out.
Allow about 10% for cutting in, roller and brush loss, and touch-ups, and more if you’re spraying, which wastes noticeably more paint outdoors in any wind.
Buy all your paint from one batch, or box the cans together, so the color stays even across large sunlit walls where mismatches show. Keep a quart sealed for touch-ups after the season.
Paint in dry, mild weather, generally between about 50 and 85 degrees Fahrenheit, out of direct hot sun and with no rain expected for a day or two. Most exterior paints need this range to cure properly.
Avoid painting late in the day when dew can settle on a fresh coat, and check your product’s low-temperature rating if you’re painting in cooler weather. Good conditions matter as much as good paint.
General Estimating Notice: This calculator sizes exterior body paint, trim, primer, supplies, and cost from your wall dimensions, gables, surface, coats, coverage, and the prices you enter, using typical 2024–2025 U.S. figures. Actual coverage varies widely with siding texture, porosity, color change, application method, weather, and applicator, so always check the can’s coverage and prime bare or repaired surfaces. Rough and masonry surfaces need substantially more paint. Buy from one batch for consistent color and paint in suitable weather. For planning purposes only.