How the calculator works
It multiplies the fence length by its height and the number of sides, scales it for the style (solid, spaced pickets or open rails), adds 15% for posts and rails, and divides by the coverage for your finish and wood, plus 10% for waste.
Stain or paint?
Stain soaks into the wood, shows the grain and wears away gradually, so recoating is simple. Paint forms a film that hides the wood and can last longer on smooth boards, but it peels when moisture gets behind it and needs scraping before repainting. Most wood fences are stained.
Why fences use more than expected
Fence boards are often rough-sawn, which can take almost twice the stain of smooth wood. Spraying is fast but wastes more product than brushing or rolling; if you spray, back-brush the first coat into the wood.
Neighbours and both sides
If you plan to stain the side facing a neighbour, ask first: you will need access to their yard, and some municipalities and homeowner associations set rules for fences on a property line.
Results are estimates. Coverage depends on the product, the tools and the wall; the rate printed on your can wins.