Fence Calculator
Use this fence calculator to count the sections, posts, rails and pickets for a fence run. Enter the total length, post spacing, height, gates, corners, and the picket width and gap, then add waste, concrete bags per post and unit prices if you want a cost estimate.
Math runs in your browser. Nothing is uploaded.
Unit prices (optional)
Fence run (without gates)
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Sections
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Posts (total)
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Of which end, corner and gate posts
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Rails
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Pickets or boards (with waste)
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Concrete bags
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Fence face area
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Estimated cost
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Run = total length − gates × gate width. Sections = run ÷ spacing, rounded up (per straight run when there are corners, assuming equal runs). Posts = sections + 1 for an open run, plus one for each gate; a closed loop has as many posts as sections. End, corner and gate posts usually need extra bracing or depth. Pickets = run ÷ (width + gap), rounded up, plus waste. Rails = sections × rails per section. 8 ft post spacing, 2 rails (3 for fences 6 ft or taller) and 1–2 bags of 50 lb concrete per post are typical starting values only; follow your material maker, local code and soil. Gate hardware, bracing, post length and burial depth are not counted.
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How it works
- How many fence posts do I need?
- Divide the run by the post spacing and round up to get sections; an open run needs one more post than sections. 100 ft at 8 ft spacing is 12.5, so 13 sections and 14 posts. Each gate adds a post, and corners that split the run into straight runs can add sections.
- What is the usual spacing between fence posts?
- 8 ft is a common default, especially when rails are cut from 8 ft boards, and spacings from about 6 to 8 ft are typical. The right spacing depends on your panels, rails and local rules, so change the spacing field to match your material.
- How many pickets or boards do I need?
- Divide the fence run by the picket width plus the gap and round up, then add waste. 100 ft is 1,200 in; with 5.5 in boards and 0.5 in gaps that is 1,200 ÷ 6 = 200, and 10% waste makes 220. Set the gap to 0 for solid privacy boards.
- How many rails per section?
- Two rails per section is a typical choice for fences under about 6 ft tall and three for taller fences. Rails = sections × rails per section, so 13 sections with 2 rails need 26 rails. The tool suggests 3 when the height is 6 ft (1.83 m) or more, and you can override it.
- How much concrete do fence posts need?
- It depends on the hole size, post size and depth. 1–2 bags of 50 lb concrete per post is a typical starting range, so 14 posts at 2 bags is 28 bags. For exact bags, use the concrete bags calculator with your hole dimensions and the bag size you will buy.