Ordering fence panels sounds like the easiest part of a fencing job, right up until you are standing in front of a run that turns a corner, stops at a gate and ends against a house wall. Order too few and the job stalls for days while you wait for another delivery. Order too many and you have paid for panels you will never use. The good news is that the maths is genuinely simple once you break the fence into straight runs. This guide walks through it step by step, and if you would rather skip the arithmetic, our fence calculator does the same sums for panels, posts and pickets in seconds.
The direct answer: divide length by panel width
For each straight run, the formula is the same: panels = fence length ÷ panel width, rounded up. Always round up, never down. You cannot buy part of a panel, and a run that works out to 9.2 panels still needs that tenth panel to reach the far post — you simply cut the last panel down to fit, or plan the final bay to suit. So measure the run, divide by the width of the panels you are buying, and round any fraction up to the next whole number.
The standard panel width behind most of those sums is 6 ft. That is true of pre-built wood and vinyl panels in the US, and it is also the standard width of featheredge panels in the UK, where a 6 ft panel is 1.83 m wide. Some vinyl systems are built around 8 ft panels instead, so check the width of the exact system you are ordering before you divide. Posts follow their own simple rule for a straight run: posts = panels + 1. Ten panels in a line need eleven posts, because there is a post at both ends of the run and one between every pair of panels.
Worked example: a 60 ft garden run
Take a single straight garden run of 60 ft, fenced with standard 6 ft panels. Divide 60 by 6 and you get exactly 10, so you need 10 panels. Posts are panels plus one, which gives 11 posts. That is the panel and post list for the run itself, before gravel boards, post caps, concrete and fixings. Many people add one spare panel to the order if the budget allows, because a panel damaged in transit or cut badly is far easier to swap on the day than a week later, when the fence is half built.
One common variation changes the post count, not the panel count. If the run ends at a house wall, a garage or an existing solid post, the last “post” in the count can be a wall fixing instead — a post or batten screwed securely into the masonry, with the final panel fixed to it. The panels stay at 10, but you buy 10 posts and a wall fixing rather than 11 posts. The same idea works at the start of a run that leaves directly from a wall.
Corners and direction changes
Corners are where panel counts most often go wrong, usually because the whole fence gets measured as one long line. Do not do that. Treat every straight run as its own small fence: measure it on its own, divide by the panel width, round up, and work out its panels and posts separately. Every corner post does double duty — it ends one run and starts the next — so the corner post itself is shared between the two runs it joins. In practice that means you add the panels from each run together, then add the posts from each run and subtract one post for every corner, because that corner post should only be bought once.
Gates need stronger posts
A gate does not add panels, and in most layouts it does not add posts either: a gate hangs between two posts that are already in your count, filling the gap where a panel would otherwise go. What a gate does change is how hard those two posts have to work. Gate posts take the strain of a heavy, moving panel every single day, so use a heavier post for them — a 6×6 timber post or a steel post — and concrete them in without exception. A gate post set in soil alone will start to lean, and the gate will drag. For how deep those posts should go and how much concrete each one takes, see our guide to fence post spacing, depth and concrete per post.
Picket fences are different
If you are building a picket fence, put the panel formula away, because there are no panels. A picket fence is built board by board, so the count runs the other way: pickets = total fence length ÷ (picket width + gap), with everything in the same units. Take pickets that are 3.5 in wide, fitted with a 0.5 in gap. Each picket takes up 4 in of fence, so you need 3 pickets for every foot — 180 pickets for a 60 ft fence, before any waste allowance. Add around 5–10% for damaged boards, bad cuts and the pickets you reject on sight.
That picket sum is the one people most often get wrong by forgetting the gap, which quietly inflates or shrinks the count across a long fence. The fence calculator has a picket mode that handles the width, the gap and the waste allowance for you, so it is worth running your numbers through it before you order a few hundred boards.
Measure honestly before you order
Every formula above is only as good as the measurement you feed it, so measure each straight run separately and measure it properly. Walk the line with a tape or a measuring wheel rather than pacing it out. Pacing drifts — a “yard” pace that is really 33 inches will under-measure a 60 ft run by several feet, which is exactly one panel short. Measure along the line the fence will actually follow, including any slope, and write each run down separately instead of carrying a single total in your head.
Before you order anything, check the boundary line itself, and whose fence it is. Boundaries on the ground do not always sit where hedges, old fences or assumptions say they do, and replacing a fence that turns out to be your neighbour’s — or building one a few inches onto their land — is an expensive argument. A short conversation with the neighbour, and a look at any plans or deeds you have, costs nothing and settles the line before the first post hole is dug.
To recap: panels are the run length divided by the panel width, rounded up; posts are panels plus one for each straight run, with corner posts shared rather than doubled; and gates change the strength of the posts, not the panel count. Once you have measured each run, run your figures through the fence calculator as a final check — it takes a minute, and it is much cheaper than a second delivery.
Frequently asked questions
How many panels for 100 ft of fence?
17 panels of 6 ft. 100 ÷ 6 = 16.67, and you always round up, so the 17th panel covers the final stretch — cut it to fit. A straight 100 ft run standing on its own needs 18 posts: one per panel, plus one at the far end.
How wide is a standard fence panel?
6 ft. That is the standard width for pre-built wood and vinyl panels in the US and for featheredge panels in the UK, where it is 1.83 m. Some vinyl systems use 8 ft panels instead, so check the width of your system before you work out the count.
Do I need a post at every corner?
Yes. A corner post ends one run and starts the next, which is why it is shared when you add the runs together rather than bought twice. Corners take wind load from two directions, so set corner posts in concrete.
Can I mix 6 ft and 8 ft sections?
Yes, within a run, as long as the posts are spaced to match each section — 6 ft spacing under the 6 ft panels and 8 ft spacing under the 8 ft panels. But panels from one system rarely fit the posts of another, so mixing widths within one system is far easier than mixing brands.