Fence Calculator
Find out how many posts, panels, rails, and bags of concrete you need for a fence — with a cost estimate.
Estimate for a straight run. Posts = sections + 1. Common spacing is 6–8 ft; set each post in 1–2 bags of fast-setting concrete.
Estimate only. These figures help you plan how much to buy — they are not engineering or structural advice. Actual needs vary with site conditions, waste, and installation method, so order a little extra and confirm final quantities with your supplier or contractor before you buy or start the job.
Popular fence lengths
Jump to a ready-made answer for a common length.
How the fence calculation works
Everything starts from fence length and how far apart you set the posts.
Fence length ÷ post spacing, rounded up.
Sections + 1 for a straight run. Add a post at every corner and end.
Panels = sections − gate openings. Rails = panels × rails per section (often 2–3).
Bags = posts × bags per post (≈ 1–2 bags of fast-setting mix each).
Sources & assumptions
Frequently asked questions
How many fence posts do I need for a 100 ft fence?
At 8 ft spacing, a 100 ft fence has 13 sections (100 ÷ 8, rounded up), so you need 14 posts — sections plus one. Closer spacing means more posts.
How do I calculate fence posts and panels?
Divide the fence length by the post spacing and round up to get the number of sections. Posts = sections + 1. Panels equal the number of sections, minus any gate openings.
How much concrete do I need per fence post?
A typical 4×4 wood or metal post set in a hole uses about 1–2 bags of fast-setting concrete mix. Taller fences, sandy soil, and gate posts may need more.
What's the right spacing between fence posts?
Most wood and vinyl fences use 6–8 ft spacing; 8 ft is common for pre-made panels. Closer spacing adds strength in windy areas or on slopes.