Fence Calculator
Estimate the posts, rails, and pickets for a wood privacy or picket fence from its run length, post spacing, and height. Set your picket width and gap to get an accurate picket count for board-on-board, spaced, or solid styles.
How to Use
- Enter the total fence length in feet — the full run you plan to build.
- Set the post spacing in feet; 8 ft is standard, drop to 6 ft for tall or windy runs.
- Enter the fence height in feet, which decides whether you need 2 or 3 rails per section.
- Enter the picket width and the gap between pickets in inches — set the gap to 0 for a solid board-on-board fence.
- Read the post, rail, and picket counts, and check the step-by-step Show Work below.
Show Work
Notes
About the Fence Calculator
The Fence Calculator is a free tool for building, materials estimation and site work. It runs right in your web browser, so there is nothing to download. Estimate the posts, rails, and pickets for a wood privacy or picket fence from its run length, post spacing, and height. Set your picket width and gap to get an accurate picket count for board-on-board, spaced, or solid styles.
How it works
Type your numbers into the boxes. The answer shows up right away — you do not have to press a button. If you change a number, the answer changes too. So you can try different numbers and watch what happens, or check an answer you worked out yourself. Just make sure each box has the right kind of number in it.
Want the deeper story? The Knowledge Base explains the ideas behind the tools in more detail.
Frequently Asked Questions
How far apart should fence posts be?
Eight feet on center is the common standard and matches stock rail and panel lengths, so it minimizes waste. Tighten to 6 feet for tall privacy fences, heavy gates, or windy and sloped sites where the extra rigidity helps. The tool divides your run by the spacing and adds one for the end post — closer spacing means more posts.
How many rails do I need per section?
Two rails — top and bottom — is fine for fences up to about 5 feet. At 6 feet and taller, add a third middle rail so the pickets do not warp or sag and the fence stays stiff. The tool picks the rail count from the height you enter, but always check your local code, which may set a minimum.
How do picket width and gap affect the count?
The tool fills each section by dividing its width by the picket width plus the gap. A wider picket or a bigger gap means fewer pickets; a tight or zero gap means more. For a solid privacy fence, set the gap to 0, and for board-on-board (overlapping pickets) you will need roughly 15 to 20% more than a flat spaced layout.
How deep should I set the posts?
A good rule is to bury about one-third of the post’s above-ground height, plus a few inches of gravel for drainage — so a 6 ft fence wants a hole roughly 2 to 3 feet deep. Always go below your local frost line so heaving does not push posts up over winter. Buy posts long enough to account for that buried portion.
Should I add waste to the picket count?
Yes — order about 5 to 10% extra pickets to cover knots, splits, cupped boards, and the inevitable cut-offs at gates and corners. Rails and posts are bought in standard lengths, so plan those around your spacing. Buying a little long also leaves matching stock for repairs down the road from the same lot.
How do I use the Fence Calculator?
Simply type your numbers and read the result, which refreshes the instant you change something. There is nothing to submit and nothing to wait for.
Is it free? Does it work without internet?
Yes to both. It is free with no sign-up, and once the page has loaded it keeps working even with no internet.
Where does my data go?
Nowhere — every calculation runs on your own device. Nothing you enter is uploaded, logged, or stored.
Common Use Cases
Building a privacy fence
Turn a yard perimeter into post, rail, and picket counts for a solid 6 or 8 ft privacy run.
Planning a picket fence
Dial in picket width and spacing to get the count and look for a classic spaced front-yard fence.
Budgeting a fence project
Get materials up front to price posts, rails, and pickets before scheduling the dig and build.
Comparing post spacing
See how 6 ft versus 8 ft spacing changes the post count so you balance strength against material cost.
Estimating a fence repair or extension
Size a new section or replacement run and order matching posts, rails, and pickets.
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