Fence calculator
Mesh, panel and timber fences by sections: posts, foundations, infill and concrete
How the calculation works
Choose the fence type (mesh, panels, timber), enter the sections with length, height and turn angle, and add gates or passages. Set the post spacing or panel width, the foundation sizes and the accessory norms. The calculator splits every section into fields, counts ordinary, end, corner, tension and gate posts (a shared post is counted once), works out infill, accessories and concrete, and shows a 2D plan and a side view.
Formula and assumptions
Fields per section = ⌈length ÷ maximum spacing⌉, posts in a run = fields + 1. Closed fence: posts = the sum of fields over all sections. Panel fence: full panels = ⌊length ÷ (panel width + post width)⌋ plus a shortened field. Timber infill: boards = rounded (clear width − gap) ÷ (board width + gap). Concrete = sum of foundation volumes − the embedded part of the post.
Worked example
An open fence of 12 m with a maximum spacing of 2.5 m: 12 ÷ 2.5 = 4.8, so 5 fields of 2.4 m and 6 posts. A closed 10 × 6 m rectangle with 4 m spacing: 3 + 2 + 3 + 2 = 10 fields and 10 posts; the open-run formula ⌈32 ÷ 4⌉ + 1 = 9 would give too few. Mesh 1.5 m high: 12 m × 1.05 = 12.6 m, so 1 roll of 25 m.
More worked examples
- A 20 m fence with a maximum spacing of 2.5 m: 8 fields and 9 posts.
- A 10 m panel fence, 2.5 m panels, 6 cm posts: 3 full panels + 1 shortened, 5 posts.
Fields and posts of an open run with a maximum spacing of 2.5 m
| Length (m) | Fields | Posts |
|---|---|---|
| 10 | 4 | 5 |
| 20 | 8 | 9 |
| 30 | 12 | 13 |
| 40 | 16 | 17 |
| 50 | 20 | 21 |
What affects real consumption
- The fence type decides the infill: mesh is counted by length, panels by pieces and timber by boards and rails.
- Angles and gates change the post types: a shared corner post is counted once, and gates have their own posts.
- Foundation size and post embedment set the amount of concrete; the embedded part of the post can be deducted.
Common mistakes
- Using the open-run formula for a closed fence gives the wrong number of posts.
- Forgetting the extra posts beside gates and passages.
- Concrete worked out without deducting the embedded post or without a reserve.
Frequently asked questions
Why does a closed fence have a different number of posts?
A closed fence has no end posts: every section ends in a post that also starts the next one, so there are as many posts as fields. The open-run formula adds one extra post.
Does the calculator check load capacity and wind resistance?
No. You set the spacing, sections and foundations or take them from the manufacturer's instructions. Post and foundation capacity needs a separate calculation.