About this tool
Fence Calculator is a free, in-browser tool that estimates every major material for a picket or privacy fence: posts, sections, rails, pickets and the bags of concrete to set the posts. All figures are computed locally as you type — nothing is uploaded.
The run is divided into sections by post spacing, so sections = ceil(length ÷ spacing) and posts = sections + 1 (one extra to close the last bay). Rails are sections × rails per section (two for shorter fences, three for taller ones). Pickets are the fence length in inches divided by the picket width plus its gap, rounded up: pickets = ceil(length × 12 ÷ (picket width + gap)). Each post is assumed to need two 50-lb bags of concrete, so concrete bags = posts × 2.
Use it to shop for a fence line: adjust the picket width and gap to match your boards and the look you want (tighter gaps use more pickets), and set the post spacing to your rail length, typically 8 feet.
Frequently asked questions
Why is the post count sections plus one?
A straight fence needs a post at both ends of every section, and neighbouring sections share a post. So a run of N sections has N + 1 posts. Corners and gates may add posts beyond this baseline count.
How is the picket count worked out?
Each picket plus its gap occupies picket width + gap inches. Dividing the fence length (converted to inches) by that spacing and rounding up gives the number of pickets. A wider gap uses fewer pickets; a tighter gap uses more.
How much concrete does each post need?
The tool assumes two 50-lb bags per post, a common figure for a standard post hole. Deeper or wider holes, or larger posts, need more — check the bag's yield and your hole size for a precise amount.
Does it account for gates and corners?
No. It estimates a straight run; add posts and hardware for each gate and corner separately. All calculations happen in your browser and nothing is uploaded.
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