Fence Calculator
Calculate posts, panels, rails and concrete for a fence run.
Please note: Material estimates for planning only. Always confirm quantities against your drawings, local building codes and supplier specifications before ordering. Structural work requires a qualified engineer.
What the Fence Calculator does
Fence posts follow the sections-plus-one rule: a run divided into sections needs a post at each end of every section, sharing posts between neighbours. Post length must include the buried depth, which is usually a third of the visible height.
Formula
Sections = ⌈Fence length ÷ Post spacing⌉Posts = Sections + 1Post length = Fence height + Hole depthConcrete per post = π × (Hole radius)² × Depth − Post volume
Inputs explained
| Input | Unit | Required | Notes |
|---|---|---|---|
| Fence length | number | Yes | Accepts more than 0. |
| Fence length unit | one of 6 options | Yes | — |
| Post spacing | number | Yes | Accepts more than 0. |
| Post spacing unit | one of 6 options | Yes | — |
| Fence height | number | Yes | Accepts more than 0. |
| Fence height unit | one of 6 options | Yes | — |
| Fence style | one of 2 options | Yes | — |
| Rails per section | number | In some modes | Accepts 1 or more. Shown Fence style is Rails and boards. |
| Board width | mm | In some modes | Accepts 10 or more. Shown Fence style is Rails and boards. |
| Gap between boards | mm | In some modes | Accepts 0 or more. Shown Fence style is Rails and boards. |
| Post hole depth | number | Yes | Accepts more than 0. |
| Post hole depth unit | one of 5 options | Yes | — |
| Post hole diameter | mm | Yes | Accepts 50 or more. |
| Price per post | selected currency | Optional | Accepts 0 or more. |
| Price per panel | selected currency | Optional | Accepts 0 or more. |
| Currency | one of 10 options | Optional | — |
How to use it
- Choose Fence length unit and Post spacing unit.
- Enter Fence length, Post spacing, Fence height and Post hole depth and 1 more.
- Fill in the remaining inputs the form shows for your choice.
- Optionally add Price per post and Price per panel.
- Select Calculate.
Worked example
A 30 m fence, 2.4 m post spacing, 1.8 m high, 600 mm holes at 300 mm diameter.
- Length
- 30 m
- Spacing
- 2.4 m
- Height
- 1.8 m
- Depth
- 600 mm
13 sections, 14 posts, each 2.4 m long. Concrete 0.0364 m³ per hole = 0.51 m³ total.
Frequently asked questions
How deep should fence posts go?
At least a quarter of the total post length, and a third for exposed or tall fences. A 1.8 m fence usually needs 600 mm buried.