Most fences use 8 ft post spacing.
MEASURE. ESTIMATE. BUILD.
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.
01 / PROJECT DIMENSIONS↙
Total wall length
Wall height
Waste %%
Change any measurement to update your estimate.
02 / YOUR MATERIAL ESTIMATE
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 − 1Sources: 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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