Free Fence Calculator
Estimate posts, rails and pickets for a fence run from its length and post spacing. Free, fast, and works entirely in your browser with no sign-up required.
Updated
Fence materials
Posts needed
14
posts
- Sections
- 13sections
- Rails
- 39rails
- Pickets
- 219pickets
How this is calculated
sections = length ÷ spacing (rounded up); posts = sections + 1; pickets = length × 12 ÷ (picket width + gap)
- Post spacing of 8 ft is typical for wood fence; 6 ft gives a stiffer run in windy or sloping ground.
- A dog-ear picket sold as "6 inch" actually measures 5.5 in — the default reflects the real width.
- Set the gap to 0 for a privacy fence, or to the spacing you want for a picket-style fence.
- Gate openings are not deducted.
Frequently Asked Questions
How does the Fence Calculator work?
It applies the formula sections = length ÷ spacing (rounded up); posts = sections + 1; pickets = length × 12 ÷ (picket width + gap). Enter your measurements and the result updates instantly in your browser — nothing is uploaded and no sign-up is needed.
Why should I include a waste allowance?
Offcuts, spillage, breakage and an uneven sub-base all consume material that the raw geometry does not account for. The default allowance is deliberately modest; increase it for complex layouts, and remember that running short usually costs more in a second delivery than the surplus did.
Are the results exact?
They are a close estimate, not a guarantee. Post spacing of 8 ft is typical for wood fence; 6 ft gives a stiffer run in windy or sloping ground. Real materials vary by supplier, moisture content and compaction, so confirm the rate with your supplier before placing a large order.
Is this tool free?
Yes, completely free with no registration. All calculations happen client-side in your browser.
Does it work on mobile?
Yes. The calculator is fully responsive and works on phones and tablets in any modern browser — useful when you are measuring on site.
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About the Fence Calculator
The Fence Calculator turns a fence length and post spacing into the posts, rails and pickets you need — including the end post that is easy to forget. Enter your measurements and the result updates as you type — there is nothing to submit and nothing to wait for.
Everything runs in your browser. Nothing you enter is sent to a server, there is no sign-up, and there is no usage limit.
Who it's for
Anyone building or replacing a fence, and suppliers putting together a materials list.
How the calculation works
sections = length ÷ spacing (rounded up); posts = sections + 1; pickets = length × 12 ÷ (picket width + gap)
The result depends on a few standard constants, which are stated on the page rather than hidden:
- Post spacing of 8 ft is typical for wood fence; 6 ft gives a stiffer run in windy or sloping ground.
- A dog-ear picket sold as "6 inch" actually measures 5.5 in — the default reflects the real width.
- Set the gap to 0 for a privacy fence, or to the spacing you want for a picket-style fence.
- Gate openings are not deducted.
- Board width is the ACTUAL width — nominal "6 inch" decking measures 5.5 in, which is the default.
- Two screws per board at every joist crossing.
- Joist count assumes a simple rectangular frame; stairs, railings and beams are not included.
- Composite and hardwood boards vary — check the actual width before ordering.
Getting an accurate estimate
Measure twice. Small errors in a linear dimension compound, because material volume scales with two or three of them at once — a 6-inch error across a 20-foot run is over a cubic foot of material on a 4-inch pour.
Keep the waste allowance. The default is deliberately conservative: offcuts, spillage, uneven sub-base and breakage are all real, and running short mid-job usually costs more in a second delivery than the surplus did.
Round up when you order. Suppliers sell in fixed increments — quarter yards, whole bags, full boxes — so treat the figure here as the minimum you need rather than the exact amount to buy.