Exterior Paint Calculator: How Much Paint for Your Siding?
Enter your home's total wall length, height, and siding type for an instant, brand-neutral estimate of how many gallons of exterior paint to buy. The calculator subtracts doors and windows, accounts for gables and coats, and adjusts coverage for your siding.
Exterior Paint Calculator
Add up the length of all your exterior walls, enter the height, and pick your siding type. The calculator subtracts doors and windows and tells you how much exterior paint to buy — for any brand.
How to use this exterior paint calculator
Walk around the house and add up the length of every exterior wall — that total is your "wall length." Enter the wall height (about 9–10 ft per story), the number of doors and windows, and your siding type, which sets a realistic coverage rate. Choose your number of coats (two for exteriors) and, if your house has gables or dormers, add their area under Advanced. Press calculate for a clear gallons-to-buy result.
How to measure your house for paint
You don't need a perfect blueprint — a tape measure and a walk around the house are enough. Measure each wall's length along the ground and add them together, then multiply by the height from the foundation to the eaves. That gives the rectangular wall area. The triangular gable sections under roof peaks are added on top: about ½ × width × height for each. Doors and windows are subtracted automatically.
Exterior paint coverage by siding type
Texture is everything outdoors. Smooth surfaces — vinyl, smooth wood, fiber cement — stretch to about 380 sq ft per gallon. Lap or clapboard siding covers around 320. Rough-sawn wood and T1-11 drink more at about 260. Stucco, brick, and block are the thirstiest at roughly 150–180 sq ft per gallon because paint has to work into every pit and pore. Pick your type and the calculator uses the matching figure.
One coat or two?
Exterior surfaces take a beating from sun, rain, and temperature swings, so two coats are the standard and are often required to keep the paint's warranty valid. Two coats also even out color and hide the surface beneath. Only consider a single coat when you're refreshing the exact same color over clean, sound paint.
Don't forget trim, fascia, and doors
The body paint estimate above does not include trim, fascia, soffits, railings, or doors. Those are usually a different color and sheen and are bought separately — plan on roughly one to two gallons of trim paint for an average house, more if it has decorative detail. A separate quart or two covers the front and back doors.
Frequently asked questions
How much paint do I need for the outside of a house?
A common single-story house has about 150 ft of wall length and 9 ft walls, or roughly 1,350 sq ft. After subtracting doors and windows and applying two coats on smooth siding (about 380 sq ft per gallon), that works out to around 7 gallons of body paint, plus separate paint for trim.
How many square feet does exterior paint cover per gallon?
On smooth siding like vinyl or fiber cement, exterior paint covers about 350–400 sq ft per gallon. Lap siding covers around 320, rough-sawn wood about 260, and porous stucco, brick, or block can drop to 150–180 sq ft per gallon. The calculator sets the right figure when you pick your siding type.
How many coats of exterior paint do I need?
Plan on two coats for exterior work. Two coats give the durability and even color that stand up to sun and weather, and they are usually required for the paint’s warranty. A single coat may do only when you are repainting the same color over sound, clean paint.
How do I measure my house for paint?
Walk the perimeter and add up the length of every exterior wall, then multiply by the wall height to get the wall area. Subtract doors and windows, and add the gable triangles under any roof peaks. The calculator does the subtraction and coat math for you.
Do I need separate paint for trim and fascia?
Yes. Trim, fascia, soffits, and doors are usually painted in a different color and often a different sheen (satin or semi-gloss), so they are bought separately. A good rule of thumb is one to two gallons of trim paint for an average house, more if it has a lot of detail.
How do I estimate paint for gable ends?
A gable is the triangle of wall under a roof peak. Its area is about one-half times the width times the height of the triangle. For a 24 ft wide gable that rises 6 ft, that is about 72 sq ft. Add each gable’s area in the calculator’s Advanced section.
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