Fence Calculator

What this fence calculator figures out

Planning a wood or vinyl fence starts with three numbers: how many posts to set, how many rails to run between them, and how many pickets to fill the gaps. This tool takes your total fence length and picket dimensions and returns all three counts instantly, so you can price a materials run before you ever leave for the lumber yard.

How the numbers are calculated

Your fence is split into sections — the spans between two posts. The number of sections is your length divided by the post spacing, rounded up. Posts equal the number of sections plus one, because a fence always needs one more post than it has gaps. Rails multiply the section count by the rails you run per section (2 is standard, 3 for taller privacy fences). Pickets are your length in inches divided by the combined picket width plus gap, rounded up so you never come up short. These are planning estimates — always confirm against your final layout and local building codes before buying, and add roughly 10% for waste and cuts.

How to use it

1. Enter the total fence length in feet (the full run you plan to build).
2. Set your post spacing — 8 ft is typical for wood fences.
3. Choose rails per section based on fence height.
4. Enter the picket width and the gap you want between pickets.
5. Read your post, rail, and picket counts — they update as you type.

FAQ

What post spacing should I use?

8 feet is the common standard for wood privacy fences. Use 6 feet for extra strength in windy areas or with heavier panels.

Why is the picket count rounded up?

You can't buy a fraction of a picket, so we round up to make sure your fence line is fully covered with no gaps left over.

Does this include gates?

No. Subtract each gate opening's width from your total length first, then add the gate hardware separately.

Should I buy exactly this many pickets?

Add about 10% extra for waste, miscuts, and warped boards you'll reject at the yard.