Fencing & decking
Fence Material Calculator
Counts the posts, rails and pickets a run needs, including the waste a takeoff has to carry.
Result
Post holes should go about a third of the fence height into the ground and below the frost line, whichever is deeper. Gates, corners and ends need heavier posts than line posts, and a fence is only as good as its corners.
Get a Free Business AuditHow the calculation works
Sections are the fence length divided by post spacing, and posts are sections plus one, because a run of three sections needs four posts. Pickets come from the length in inches divided by the picket width plus whatever gap you are leaving, so a spaced picket fence needs noticeably fewer boards than a solid one. Rails are the number of sections times the rails per section. The reason to count rather than estimate is that pickets are the largest line and a small error in the gap assumption compounds across a long run.
What moves the number
- Post spacing, since wider spacing uses fewer posts and puts more load on each rail.
- Picket width and gap, which together decide the picket count and are easy to assume wrongly.
- Rails per section, as three rails are usual above a certain height and two below.
- Waste allowance, because boards are not all usable and cuts at corners and gates consume material.
Where this one goes wrong
Buy pickets with an allowance for grade rather than counting exactly. A bundle of fence boards contains some that are badly bowed, split at the end or too knotty to use in a visible face, and a takeoff with no allowance sends someone back to the supplier mid-job. Corners and gate posts also need a rethink rather than being counted as line posts: a corner post takes load from two directions and a gate post takes the gate's weight and swing, so both are usually larger and set deeper than the run. Count them separately.
Before you quote
- Add a waste allowance for unusable boards rather than counting exactly.
- Count corner and gate posts separately, since they are a different size.
- Confirm the picket gap, as that decides the largest material line.
Questions
About this calculator
How many posts does a fence need?
Divide the run by your post spacing and add one, because a run of sections always needs one more post than sections. Corners and gate positions add posts beyond that, and those are usually a larger size set deeper, so they are worth counting separately rather than as part of the run.
How many pickets per foot of fence?
It depends on the picket width and the gap. Twelve inches divided by the picket width plus the gap gives pickets per foot, so a solid fence with no gap uses considerably more than a spaced one. Getting that gap right matters because pickets are the biggest material line.
How much waste should I allow on fence material?
Enough to cover boards you cannot use in a visible face, plus offcuts at corners and gates. Fence grade lumber includes some bowed, split and heavily knotted pieces, and a takeoff that counts exactly means a trip back to the supplier partway through the job.
The formula
sections = length / spacing; posts = sections + 1; pickets = length in inches / (picket width + gap)
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How to use this calculator
- Fence length (ft) (ft). Enter your own figure; the page starts at 150 ft.
- Post spacing (ft) (ft). Enter your own figure; the page starts at 8 ft.
- Fence height (ft) (ft). Enter your own figure; the page starts at 6 ft.
- Rails per section. Enter your own figure; the page starts at 3.
- Picket width (in) (in). Enter your own figure; the page starts at 5.5 in.
- Gap between pickets (in) (in). Enter your own figure; the page starts at 0 in.
The result updates as you type, so you can try a figure, see what it does to posts, 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 |
| Post spacing (ft) | 8 ft |
| Fence height (ft) | 6 ft |
| Rails per section | 3 |
| Picket width (in) | 5.5 in |
| Gap between pickets (in) | 0 in |
What comes out
| Result | Value |
|---|---|
| Posts main result | 20 |
| Sections | 19 |
| Rail material | 456 |
| Pickets | 328 |
| 60 lb concrete bags | 40 |
20 posts across 19 sections, 456 feet of rail and 328 pickets, plus about 40 bags of concrete for the holes.
How sensitive the answer is
Holding everything else steady and changing only fence length (ft), this is what happens to posts. It is worth knowing which of your inputs the answer actually hinges on, and which barely move it.
| Fence length (ft) (ft) | Posts |
|---|---|
| 75 ft | 11 |
| 113 ft | 16 |
| 150 ft example above | 20 |
| 225 ft | 30 |
| 300 ft | 39 |
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.
- Post spacing (ft) (ft)
- Measured in ft, between 3 and 16, starting at 8 ft.
- Fence height (ft) (ft)
- Measured in ft, between 0 and 12, starting at 6 ft.
- Rails per section
- A number, between 0 and 8, starting at 3.
- Picket width (in) (in)
- Measured in in, between 0 and 12, starting at 5.5 in.
- Gap between pickets (in) (in)
- Measured in in, between 0 and 8, starting at 0 in.
What the results tell you
| Result | What it is |
|---|---|
| Posts | The headline result. A number. |
| Sections | A number. |
| Rail material | A number. |
| Pickets | A number. |
| 60 lb concrete bags | A number. |
Keep going
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