Fence Calculator

How to use the fence calculator

Walk the fence line with a long tape or measuring wheel and enter the total run in feet — all sides you’re fencing, added together. Count every gate (each one replaces a panel but keeps its posts), and add the number of corners under Advanced: a corner ends one straight run and starts another, which costs one extra post beyond the simple line math.

Before anything else: call 811 a few days before you dig. Utility locating is free, hitting a gas or fiber line is neither, and every post hole is a small excavation. While you wait, mark the line with stakes and string — measuring along the string is how the pros get honest lengths on sloped or curved yards.

Post spacing drives the whole bill of materials. Eight feet is the standard for pre-built panels and rail kits — maximum coverage per post and per hole. Six-foot spacing buys a stiffer fence: shorter spans flex less in wind, sag less under wet pickets, and suit tall privacy fences in gusty, open yards. Match the spacing to the panels you’re actually buying — a fence built of 8 ft panels needs 8 ft spacing, full stop.

Set posts deep: the working rule is one-third of the post’s length in the ground, with 24 inches as the floor and below your local frost line in cold climates. That’s why a 6 ft privacy fence is built from 8 or 9 ft posts — 6 ft showing, 2–3 ft buried. As a flagged estimate to verify against your bag labels: a typical 4 × 4 post in a 10-inch-diameter hole 2 ft deep takes about two 50 lb bags of fast-setting concrete; 6 ft privacy-fence posts in bigger holes run three to four. Multiply by the post count before the store run — concrete is the line item everyone underestimates.

Read the outputs together: posts is the dig-and-set number, panels is what goes on the rack at checkout, and gates ride along as prefab units or hardware kits. Buy panels last if your run has a remainder section — a 100 ft run at 8 ft spacing ends in a half-width section, which most people fill by cutting one panel down rather than buying a custom size.

The formula

Section math with the classic fencepost off-by-one, plus corner posts and gate substitutions:

sections = total length ÷ post spacing, rounded UP
posts = sections + 1 + corners
panels = sections − gates   [never below 0]

Worked example with the defaults: a 100 ft run at 8 ft spacing is 100 ÷ 8 = 12.5 → 13 sections. Posts are sections plus one — 14 — and with one gate, panels are 13 − 1 = 12. Tighten to 6 ft spacing and the same run becomes 17 sections, 18 posts, 16 panels.

The +1 is the fencepost problem: a fence of N sections always has N + 1 posts, because both ends need one. Corners add a post each without adding sections; gates remove a panel each without removing posts — the gate hangs between the same two posts the panel would have.

Frequently asked questions