The short answer
A 100 ft run with 8-foot panels is 12.5 panels, so you need 13. You cannot buy half a panel, so 13 panels cover 104 ft, which leaves 4 ft to absorb or trim.
How to calculate fence panels
- Measure each straight run including any gate openings.
- Split the run at every gate. Each stretch of fence between gates or ends is a span.
- Divide each span by the panel width you will actually buy, commonly 6 or 8 feet for panel fences.
- Round each span up to a whole panel, then add the spans.
Why rounding each span matters
Some calculators subtract the gate widths from the total and divide once. That can undercount, even when the total divides evenly, because each span between the gates rounds up on its own. Take a 120 ft run with two 4-foot gates and 8-foot panels. The fence footage is 112 ft, and 112 ft ÷ 8 ft is 14 panels, so dividing the total gives 14.
| Fence footage | 120 ft − 8 ft = 112 ft |
|---|---|
| Dividing the total | 112 ft ÷ 8 ft = 14 → 14 panels |
| Spans between the gates (panels) | 28 ft (4) + 56 ft (7) + 28 ft (4) |
| Rounding each span | 15 panels |
The gates leave three separate spans, and each one rounds up on its own, so the order is 15 panels, not 14. Ordering from the total would be 1 short.
Choosing the panel width
Panel width changes both the count and the remainder. A single 64 ft run with no gates:
| 4 ft panels | 16 panels, no remainder |
|---|---|
| 6 ft panels | 11 panels, 2 ft over |
| 8 ft panels | 8 panels, no remainder |
The width that fits the run exactly, here 8 feet, avoids a remainder. In practice you buy the width your supplier stocks, and the right choice also depends on the style, the height and how the panels attach to the posts.
A whole yard with corners
Corners do not change panel counts the way they change posts; each side is its own span. An 80 ft by 60 ft yard with no gates and 8-foot panels needs 36 panels. Dividing the 280 ft perimeter by 8 feet and rounding once would give 35, one short, because the 60 ft sides are 7.5 panels each and round up to 8. With 6-foot panels the sides need 48 panels in total, against 47 from dividing the perimeter once.
A quick way to check your order
Write the spans on a list with the panel count beside each one, and add the column. Then check the list two ways: add the span widths and confirm they equal the fence footage (the run length minus the gates), and re-divide each span by the panel width. If the widths do not add up, a span was mis-measured; if a division differs, a span was mis-rounded. Do not compare against one division of the whole footage, which is the shortcut that undercounts. The list is also what you hand to the supplier or your installer, so they can see how the order was built rather than just the total.
Six-foot or eight-foot panels
Panel width changes both the count and the remainder, and which width leaves less over depends on the span. The 64 ft run above fits 8-foot panels exactly and leaves 2 ft over with 6-foot panels. A 60 ft span goes the other way: 6-foot panels fit it exactly (10 panels) and 8-foot panels need 8 with 4 ft over. Try both widths on your actual spans and note the remainder on each; then choose based on your product, your budget and how the fence will look at corners and gates.
What a panel count does not include
The count is for panels only. It does not include posts (see how to calculate fence posts), gates, rails or pickets if you build rather than buy panels, concrete, fasteners, caps or waste. Whether to order spare panels is your decision; the numbers on this page do not add any.
How the remainder is handled
When a span is not a whole number of panels, the counts here assume posts are spaced evenly across the span, so each panel is slightly narrower than its nominal width. Check that your product allows panels set slightly narrower than nominal, or plan to trim.
Assumptions used on this page
- Level, straight runs measured in feet; panel widths of 4, 6 or 8 feet as stated.
- Gates are 4 feet wide and spaced evenly along the run where they appear.
- No waste or spare allowance, and no allowance for slopes.
- All examples are fictional and are calculated with the same planner as the fence panel calculator.
Questions
How many 8-foot panels do I need for 100 feet of fence?
13 panels for an uninterrupted run. If a gate splits it, the number can change; see how gate openings change fence footage.
Do I subtract the gates first?
Yes for footage, but still round each span separately when you count panels.
Do I need extra panels?
Only if you want spares for damage or cuts. That is a purchasing choice, not part of the planning count.
How do I turn panels into a price?
Price the fence per foot and each gate separately. The fence estimate guide shows a worked example.