How this is calculated
Panels are the fence length divided by panel width, rounded up. Posts are the length divided by post spacing, plus one end post. Most panel systems use two horizontal rails per section.
This assumes a straight run on level ground. Slopes, gates, and corner posts need extra parts the linear model does not add automatically.
Measure the run along the ground where the fence will sit, not the property line on a title plan if those differ. Inside corners and dog-legs should be split into straight segments and added.
Panel height changes wind load and post size more than panel count. A taller privacy fence on the same length still uses the same bay math only when panel widths match — the concrete and post section may not.
Formula & methodology
Panels = ceil(Length ÷ panel width). Posts = ceil(Length ÷ spacing) + 1. Rails ≈ panels × 2.
Worked example
A 100 ft run, 8 ft panels, posts every 8 ft
- 1.Panels = 100 ÷ 8 = 12.5 → 13 panels
- 2.Posts = 100 ÷ 8 + 1 = 14 posts
- 3.Rails ≈ 26 rail lengths (top and bottom)
Frequently asked questions
Panel width vs post spacing?
They are often the same on pre-made panel systems. On post-and-rail builds you may set spacing independently — enter what matches your design.
Corner and gate posts?
Add one extra post per corner and two posts per gate opening beyond this straight-run count.
Concrete for posts?
Post hole concrete is not included. Use the Concrete Bag Calculator on each hole size or the main Concrete Calculator for a continuous footing.
Sloped ground?
Stepped or racked panels change panel count slightly. Order one extra panel on long runs with grade change.
Labour cost?
Materials only here. Installation is often priced per linear foot — add it through the Project Cost Estimator.
Metric fences?
Enter length and panel size in metres. Post spacing in metres works the same way.
Do I need gravel under post concrete?
Many installs put a little gravel in the hole for drainage before concrete. That volume is tiny compared with the fence panels — estimate it separately if your soil holds water.
Pickets vs panels?
If you are building from individual pickets, convert the run into panel-width bays or count pickets from spacing. This tool is aimed at panelised systems.
Last updated 2026-09-01. Formulas are planning methods — confirm with a supplier before you order.