Fence panel calculator
Calculate how many pre-assembled fence panels you need, in full panels plus one cut panel for any leftover run.
Fence calculator
Enter your specs. Every result updates live and shows its formula.
Overview
Pre-assembled panel fencing (vinyl, aluminum and some composite systems) is counted differently from a picket fence: this calculator divides your run by panel width, counts the full panels that fit, and adds one cut panel if there is a remaining stretch that does not divide evenly.
Post spacing has to match panel width exactly for a panel system, since each post-to-post span holds exactly one panel by design.
Common mistakes
- Rounding down instead of up on a run that leaves a remainder, which comes up one panel short at the end of the fence.
- Mismatching post spacing and panel width, leaving a gap or overlap the panel was not manufactured to fill.
- Ordering a cut-size panel when the supplier only sells full panels, which is why a cut panel is counted as a full one.
Related calculators
- Vinyl fence calculator Calculate panels, posts and post caps for a vinyl fence from your run length and panel width, in a privacy, picket or panel style.
- Aluminum fence calculator Calculate panels and posts for an ornamental aluminum fence, with a note on the common 4 foot minimum height for pool code compliance.
- Fence cost calculator Estimate total fence cost from run length, height and your local material and labor rates, with the budget math shown.
Related reading
In-depth guides
Frequently asked questions
How is a cut panel counted?
If your run does not divide evenly by panel width, this calculator adds one additional panel to cover the remainder, since a partial panel still commonly means cutting or special-ordering one full panel.
What is the formula for panels needed?
Divide the run length by the panel width and round up. The full count is the number of whole panels that fit, and the remainder is covered by one cut panel.
Do all panel systems use the same panel widths?
No. 6 and 8 feet are common for vinyl, and ornamental metal panels often run 4 to 6 feet, so always confirm the width of the exact product you plan to buy before setting post spacing.
Why must post spacing match the panel width?
Because a panel is manufactured to span exactly one post-to-post section. If the spacing does not match the panel width, the panel will not fit, and shimming or cutting defeats the system's strength.
Can I use this calculator for wood panel sections?
You can for pre-built wooden sections, but most wood fences are built board-by-board, in which case the wood and picket calculators give the real take-off. Panel math is for systems sold as complete sections.
What happens at a corner or a gate with panels?
Corners need a special corner post and the panels meet at the post; gates are an opening that removes run length and adds two posts, exactly like the gate logic in the full calculator.
How much extra should I order for panel fences?
There is little field-cutting in a panel install, so over-ordering one panel for damage is a common practical allowance rather than a mathematical need. Start from the exact roll-up count this calculator gives.
How do I handle a run with an odd measurement at the end?
Leave a bit of spare panel material from a full panel rather than special-ordering a one-off width, since the cost is usually driven by the full panel anyway. Trimming a full panel to the final length is the standard field solution.