Fence Calculator
Planning a fence requires knowing exactly how many posts, rails, and pickets to buy. This fence calculator estimates all three based on your total perimeter, post spacing, and number of rails per section — giving you a complete material list before you buy.
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Formula
Posts = ceil(Perimeter / Spacing) + 1; Rails = Sections × Rails per Section
Dividing the perimeter by post spacing gives the number of sections. Adding 1 accounts for the final closing post. Rails equal the number of sections times rails per section. Pickets are estimated at 2 per linear foot for standard 6-inch pickets.
How to use the Fence Calculator
- 1
Enter your total perimeter (ft)
Value should be in ft.
- 2
Enter your post spacing (ft)
Value should be in ft.
- 3
Enter your rails per section
- 4
Read your results instantly
Results update in real time as you type.
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Planning Your Fence Layout
Before buying materials, walk the fence line and mark post locations with spray paint or stakes. Account for gates — each gate requires two posts and a gate width (typically 4 feet for pedestrian, 10–12 feet for vehicles). Check property lines before digging; installing a fence on a neighbor's property can be costly to resolve. Contact 811 (USA) before digging to locate underground utilities.
Post Depth and Concrete
Posts must be buried at least one-third of their total length for stability. For a 6-foot fence, use 8-foot posts buried 2 feet deep. In frost zones, bury posts below the frost line to prevent heaving. Set posts in concrete using fast-setting concrete — pour dry mix directly in the hole and add water. Two 50-lb bags of concrete per post are typical for 4×4 posts.
Tips & Insights
Call 811 Before Digging
In the US, call 811 at least 3 business days before digging any post holes. Utility companies will mark underground lines at no charge, preventing dangerous and costly accidents.
Check for Gates in Your Perimeter
Subtract gate openings from your perimeter before calculating materials, but add gate posts separately. Each gate section needs two posts and typically a brace rail or diagonal support.
Use Pressure-Treated Wood
For wood fences, always use pressure-treated lumber rated for ground contact (UC4B or better) for posts. Above-ground components can use lighter PT grades or naturally rot-resistant wood like cedar.
Worked Examples
Backyard Privacy Fence
21 posts, 60 rails, and approximately 320 pickets for a standard privacy fence.
Small Dog Kennel
11 posts, 20 rails, and 120 pickets for an enclosed kennel run.
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Frequently Asked Questions
How far apart should fence posts be?
Fence posts are typically spaced 6–8 feet apart for wood privacy fences. Chain-link fences use 10-foot spacing. Always check the span rating of your fence panels or rails.
How deep should fence posts be set?
Posts should be buried one-third of their total length. A 6-foot above-ground fence needs 8-foot posts set 2 feet deep. In cold climates, set posts below the frost line.
How much concrete do I need per fence post?
Two 50-lb bags of fast-setting concrete per 4×4 post is typical. For 6×6 posts or loose soil, use 3 bags. Mix dry in the hole and add water per package instructions.
Can I install a fence on a property line?
You can, but it's best to place the fence a few inches inside your property line to avoid encroachment disputes. Get a survey if the line is unclear. Many jurisdictions require a neighbor notification before construction.
What is the cheapest type of fence?
Chain-link fencing is generally the cheapest per linear foot. Wire fencing (split rail with wire mesh) is also economical. Wood fencing varies widely by species; treated pine is usually the most affordable wood option.
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