Fence Paint Quantity Calculator
Painting a fence is mostly about area, and the area is easy to underestimate because a fence usually has two sides. This fence paint calculator works out how many gallons you need from the fence length, its height, how many sides you are painting, and the coverage rating printed on your paint or stain. Multiply length by height to get the area of one face, multiply by the number of sides, and divide by the coverage per gallon to find the gallons. A solid board fence presents close to its full geometric area, while a picket or rail fence has gaps that reduce the painted surface, so treat the result as an estimate for open styles and round generously for solid ones. Coverage depends heavily on the wood: rough or bare timber drinks far more paint than smooth, primed boards. Every figure here is computed deterministically from your inputs, so the same fence and coverage always return the same quantity. Enter your measurements below to size a paint order before you start, compare painting one side versus both, or check a leftover can, with a worked example that reconciles exactly to the calculator defaults so you can follow each step before buying.
Gallons equal fence length times height times the number of sides, divided by coverage per gallon. A 100 ft long, 6 ft high fence painted on 2 sides at 300 sq ft per gallon needs 4.00 gallons.
Fence paint formula
area = fence length x fence height x number of sides
gallons = area / coverage per gallon
length and height in feet, coverage in square feet per gallon
Length times height gives the area of one face. Multiplying by the number of sides accounts for painting the back as well as the front. Dividing by coverage gives the gallons required.
Worked example
Take a fence 100 feet long and 6 feet high, painted on 2 sides, with paint rated at 300 square feet per gallon.
- Area of one side: 100 x 6 = 600 sq ft
- Total area for 2 sides: 600 x 2 = 1,200 sq ft
- Gallons needed: 1,200 / 300 = 4.00 gallons
You need 4.00 gallons of paint, which matches the calculator's default inputs exactly. Buy a little extra for touch-ups and waste.
Fence Paint Quantity Calculator: frequently asked questions
Should I paint one side or both?
For a boundary fence you usually paint the side that faces you, but painting both sides protects the wood far better and looks tidy from every angle. Set the number of sides in the calculator to match what you intend to paint.
Does a picket fence use less paint?
Yes. Pickets, rails, and lattice have gaps, so the actual painted area is less than length times height. The calculator gives the area for a solid fence, so for open styles treat the result as a generous upper estimate and adjust down if you wish.
Why does coverage differ between cans?
Rough, weathered, or bare timber absorbs much more paint than smooth, primed boards, so coverage can range widely. Always use the coverage figure on your specific product, and expect a first coat on bare wood to use more than later coats.
How do I handle a second coat?
If you plan two coats, run the calculator with the number of sides set as normal and then double the gallons, or simply add the per-coat gallons together. A second coat on a sealed first coat usually uses less paint than the first.
Should I include posts and rails?
The length times height calculation already covers the visible face of a solid fence including its rails. Standalone posts that stick up above the fence line add a little extra area, so round up your purchase to allow for them.
Official sources
- Measurement, units and dimensional standards: US National Institute of Standards and Technology (NIST). As at 25 June 2026.
Reviewed by the CalculatorHub team, edited by James Graham, 25 June 2026. See our methodology. This is general information, not financial, tax, legal or investment advice.