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Fence Calculator

Enter your fence length and post spacing to get the number of posts, rails, and pickets, plus the bags of concrete for the post holes. Most fences use 8 ft post spacing.

You need approximately
40 sections
covers 320 ft² (incl. waste)
Area to cover
320 ft²
Exact amount
40 sections

Field notes

Set your corner and end posts first, string a line between them, and space the rest to that line — eyeballing post spacing leaves a fence that waves. Dig post holes about a third of the post height deep and below your frost line, or a winter heave will lift them. Budget one to two bags of fast-setting concrete per post; the calculator counts sections, but the hole depth is what holds the fence up.

How the fence calculator works

The math behind the tool:

posts = ceil(length ÷ spacing) + 1
sections = posts − 1

Sources: American Wood Council (wood post and rail spans).

Frequently asked questions

How many fence posts do I need?

Divide the fence length by the post spacing (commonly 8 ft) and add one for the end post. A 100 ft fence at 8 ft spacing needs about 14 posts.

How much concrete per fence post?

A typical 4×4 post in a 10-inch-wide, 2-foot-deep hole uses about one to two 50 lb bags of fast-setting concrete per post.

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