Fencing & decking
Fence Panel Calculator
Counts prefabricated panels, where the run almost never divides evenly.
Result
Panels come in fixed widths, so the last one almost always needs cutting. Plan where that cut lands: a narrow panel looks much better at an inside corner or against the house than in the middle of the front boundary.
Get a Free Business AuditHow the calculation works
Panels are the run less gate widths divided by the panel width, rounded up. The rounding is the whole point: panels come in fixed widths, so a run that does not divide evenly leaves a gap that has to be dealt with, and the takeoff has to say how. The options are cutting a panel down, adjusting the post spacing across the run to absorb the difference, or accepting a narrower final bay. Each has a visual consequence, and deciding before ordering is better than improvising at the last post.
What moves the number
- Panel width against the run, which determines how much of a remainder there is.
- Whether panels can be cut, since some constructions cut cleanly and others do not.
- Gate widths, which remove panels and add posts.
- Slope, because rigid panels either step down or need racking, and not all panels rack.
Where this one goes wrong
Slope is where panel fences go wrong. A rigid panel on sloping ground has to either step, leaving a triangular gap under each panel, or rack, which only works on panels designed to. Forcing a non-racking panel out of square breaks it or leaves it visibly distorted. Decide which approach the site needs before ordering, because the panel type follows from it. The other thing worth planning is where the odd bay goes: putting the narrow panel at an inconspicuous end rather than beside the gate is a small decision that makes a visible difference.
Before you quote
- Decide how the remainder is absorbed before ordering.
- Confirm the panels rack if the ground slopes and stepping is not wanted.
- Place the odd bay somewhere inconspicuous rather than at the gate.
Questions
About this calculator
What if the fence run does not divide evenly into panels?
You either cut a panel, spread the difference by adjusting post spacing across the run, or accept a narrower final bay. All three are normal. Deciding which before ordering matters because it affects the panel count and where the odd bay ends up.
Can fence panels be used on a slope?
Either by stepping them, which leaves a triangular gap beneath each panel, or by racking them, which only works with panels designed for it. Forcing a rigid non-racking panel out of square damages it. The site decides which approach, and that decides the panel type.
Are panels cheaper than building a fence board by board?
Usually faster to install and therefore cheaper in labour, which is most of a fence cost. The trade is less flexibility: a board built fence absorbs an awkward run and a slope without thought, while panels impose their width and need planning around both.
The formula
panels = (length - gate widths) / panel width, rounded up
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How to use this calculator
- Fence length (ft) (ft). Enter your own figure; the page starts at 150 ft.
- Panel width (ft) (ft). Enter your own figure; the page starts at 8 ft.
- Gates. Enter your own figure; the page starts at 1.
- Gate width (ft) (ft). Enter your own figure; the page starts at 4 ft.
- Cost per panel ($). Enter your own figure; the page starts at $78.
The result updates as you type, so you can try a figure, see what it does to panels needed, and change it back. Nothing you enter is sent anywhere or saved.
A worked example
These are the figures the calculator opens with. Every number in the results column below is produced by the same calculation the page runs, so you can follow it through before putting your own figures in.
What goes in
| Input | Value |
|---|---|
| Fence length (ft) | 150 ft |
| Panel width (ft) | 8 ft |
| Gates | 1 |
| Gate width (ft) | 4 ft |
| Cost per panel | $78 |
What comes out
| Result | Value |
|---|---|
| Panels needed main result | 19 |
| Posts | 21 |
| Offcut at the end | 6.0 |
| Panel cost | $1,482 |
19 panels and 21 posts, leaving 6.0 feet to cut down at the end of the run.
How sensitive the answer is
Holding everything else steady and changing only cost per panel, this is what happens to panels needed. It is worth knowing which of your inputs the answer actually hinges on, and which barely move it.
| Cost per panel ($) | Panels needed |
|---|---|
| $39 | 19 |
| $59 | 19 |
| $78 example above | 19 |
| $117 | 19 |
| $156 | 19 |
Every other input is held at the example value while this one changes, which is not how a real job behaves. Treat it as a guide to which number matters most, not as five separate quotes.
What each figure means
- Fence length (ft) (ft)
- Measured in ft, starting at 150 ft.
- Panel width (ft) (ft)
- Measured in ft, between 2 and 16, starting at 8 ft.
- Gates
- A number, between 0 and 10, starting at 1.
- Gate width (ft) (ft)
- Measured in ft, between 0 and 20, starting at 4 ft.
- Cost per panel ($)
- A money amount, starting at $78.
What the results tell you
| Result | What it is |
|---|---|
| Panels needed | The headline result. A number. |
| Posts | A number. |
| Offcut at the end | A decimal figure. |
| Panel cost | A money figure. |
Keep going
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