Fence Panel and Post Calculator
A fence is the fencepost problem made literal: a run of ten bays needs eleven posts, and the person who orders ten is the reason the last panel ends up propped against the shed. Then the run rarely divides by the panel width, so the last bay has to be cut — better to know that before the delivery arrives than after.
What this generator does
Divides the run into bays of a panel plus a post, counts one more post than there are bays, works out the cut bay if there is one, and sizes the posts and the concrete.
How to use this tool
- Measure the run and type it in metres.
- Set the panel width — 1830mm is the standard six-foot panel.
- Choose the posts and the fence height.
- Read the panels, the posts, the boards and the concrete.
Understanding the controls
- Length of the run
- The whole run in metres, measured where the fence will actually go — post face to post face, or wall to wall.
- Panel width
- A standard panel is 1830mm, which is six feet. Closeboard and continental panels differ, so take it from the supplier.
- Fence height
- Above ground. A quarter of the post goes below, with a minimum of 450mm, which is what sets the length of post to order.
- Posts
- Timber in two common sizes, slotted concrete, or metal spikes. Spikes are driven rather than set, so they need no concrete — which changes the order considerably.
- Gravel boards
- A board under each panel keeps the timber off the ground. One per bay, including the cut one.
Common use cases
- Ordering a garden fence without going back for one more post
- Working out whether the run needs a cut panel and how wide it would be
- Sizing posts for a fence of a given height
- Counting bags of postcrete before hiring a mixer you do not need
- Comparing concrete posts against timber on the order
How this generator works
Each bay is a panel plus the post beside it, and the run needs one more post to finish — that is the identity the whole calculation turns on, and the check states it explicitly. What is left after the whole bays becomes a cut panel, unless it is too narrow to be worth cutting, in which case it is better shared between two bays than left as a sliver. The fence is then added back up — panels, cut bay and posts — and must measure no more than the run it was cut from. Post length is the height above ground plus a quarter of it below, with a 450mm minimum, and the concrete is the hole's volume less the post's.
Randomness and fairness
Nothing is random. The same run always gives the same order.
For how randomness is produced across the whole site, see how Generate Random works.
Limitations and good to know
- Sloping ground needs stepped or raked panels, which changes the count and is not modelled here.
- Post depths are the usual domestic rule; exposed sites and tall fences want more, and a professional will say so.
- Postcrete coverage varies by brand; the figure here is for a typical 20kg bag.
- Corners and gates need their own posts, which are not counted in the run.
Privacy and your data
The order is worked out in your browser. No measurements about your garden are transmitted or stored.
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