Why is it panels plus one post?

A single panel needs a post at each end, so two. Add a second panel and it shares one, needing three. The pattern is always one more post than panels, and each gate then adds one further post because a gate needs a post on both sides.

What if my run does not divide evenly?

It usually will not. You end up with one short panel, and the calculator shows you how wide it will be. Buy a full panel and cut it down. If the offcut would be very narrow, it often looks better to trim two panels slightly rather than leave a sliver at one end.

Does this cover corners?

No. A run that turns a corner needs a post at the corner itself, so add one post per corner. It is easiest to treat each straight section as its own run and add the results.

How much concrete do the posts need?

That depends on the hole size and post depth, not on the fence, so it is not included here. As a rule of thumb the hole is about a third of the post height deep and three times the post width across.

Do I need the rails figure?

Only if you are building panels from scratch. Pre-made panels arrive with their rails already in them, so the number is there for people making their own.

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Fence Panel & Post Calculator

How many fence panels and posts a run needs, allowing for gates, plus the rails and the concrete holes to dig.

Enter the length of the run, the panel you are buying and any gates. This works out the panels, the posts, and how many holes you are digging.

Your details

Total fence length(ft)

Panel width(ft)

6 ft and 8 ft are the common widths.

Number of gates(gates)

Width of each gate(ft)

3-4 ft for a path, 10-12 for a drive.

Rails per panel(rails)

3 for a 6 ft fence, 2 for anything lower.

Result

Panels needed

Gates taken off the run first, then rounded up.

Posts neededOne at each end, one between each pair, and one more per gate.: 14
Rails neededOnly if you are building panels rather than buying them made up.: 36
Run to fill with panelsTotal length minus the gate openings.: 96
Width of the last panelThe offcut at the end. Equal to a full panel if the run divides evenly.: 8

About this tool

How Many Fence Panels and Posts Do I Need?

Take the gates off the run, divide by the panel width, and add one post. The arithmetic, the off-by-one everyone hits, and what to check before digging.

Free download

Fence Run Planning Sheet

Walk the line, write down each straight run, and total the materials. Same rules this calculator uses.

Free, no email required — print it or save it as a PDF.

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Fence Panel & Post Calculator infographic

The key numbers as one image — free to save, share, or embed on your own site with credit.

How this is calculated

Gates are taken off the run first, because a gate opening is filled by the gate rather than by panels. What is left is divided by the panel width and rounded up. Posts are panels plus one, because a line of panels needs a post at each end as well as between each pair. Each gate then adds one more post: the gate sits between two posts, one of which is already there from the panel run. Rails are counted per panel. Three is typical for a 6 foot fence and two for anything lower, which is why it is an input rather than a fixed number. A run that does not divide evenly by the panel width leaves a short panel at one end. The calculator rounds up, so that final panel is counted as a whole one - which is what you buy, then cut. This assumes one straight run. A fence that turns a corner needs a post at each corner, so add one post per corner. Post concrete is a separate calculation.

Common questions

Why is it panels plus one post?: A single panel needs a post at each end, so two. Add a second panel and it shares one, needing three. The pattern is always one more post than panels, and each gate then adds one further post because a gate needs a post on both sides.
What if my run does not divide evenly?: It usually will not. You end up with one short panel, and the calculator shows you how wide it will be. Buy a full panel and cut it down. If the offcut would be very narrow, it often looks better to trim two panels slightly rather than leave a sliver at one end.
Does this cover corners?: No. A run that turns a corner needs a post at the corner itself, so add one post per corner. It is easiest to treat each straight section as its own run and add the results.
How much concrete do the posts need?: That depends on the hole size and post depth, not on the fence, so it is not included here. As a rule of thumb the hole is about a third of the post height deep and three times the post width across.
Do I need the rails figure?: Only if you are building panels from scratch. Pre-made panels arrive with their rails already in them, so the number is there for people making their own.

Take it further with AI

Copy this into ChatGPT or Claude with your own numbers filled in. It hands over the figures this calculator worked out, so the answer is built on real arithmetic instead of a guess.

I used the Fence Panel & Post Calculator at https://www.bfcbrilliance.com/tools/fence-calculator.

What I entered:
- Total fence length (ft): ___
- Panel width (ft): ___
- Number of gates (gates): ___
- Width of each gate (ft): ___
- Rails per panel (rails): ___

What it calculated:
- Panels needed: ___
- Posts needed: ___
- Rails needed: ___
- Run to fill with panels: ___
- Width of the last panel: ___

Use those figures as given — they are already worked out, so please don't recalculate or estimate your own. Help me turn them into a plan: what to buy or do, in what order, roughly what it should cost, and the mistakes people most often make with this job.

Where the job touches structure, gas, or electrics, tell me to check local building code and whether a permit or a licensed trade is required.

Last updated Jul 31, 2026

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