Fence Calculator

Fence materials depend on the total fence length, the maximum post spacing you are working to, the rails per section, the picket width and gap, and any gates or corners in the layout. The basic relationships are:

• Sections = Fence Length ÷ Post Spacing, rounded up
• Posts = Sections + 1 for a simple open straight run
• Rails = Sections × Rails Per Section
• Pickets = Fence Length ÷ (Picket Width + Gap), rounded up

1. 1Enter the fence length, or switch to multiple runs and enter each side.
2. 2Enter the maximum post spacing for your fence design.
3. 3Enter the rails per section.
4. 4Enter the picket width and the gap between pickets.
5. 5Add gates and corners if your layout has them.
6. 6Enter the post-hole dimensions if you want concrete included.
7. 7Choose the picket waste and concrete allowances.
8. 8Optionally enter your local material prices.
9. 9Select Calculate and review the bill of materials.

Divide the fence length by the maximum spacing, round up to get the number of sections, then add one closing post for an open run. For a 100 ft fence at a maximum spacing of 8 ft: 100 ÷ 8 = 12.5, which rounds up to 13 sections, giving 13 + 1 = 14 posts. Gate posts and corner posts are then added exactly as you specify them, and each is shown separately in the results.

If the division gives 12.5 sections, building only 12 would make each section wider than the maximum spacing you entered. The calculator therefore uses 13 sections and shows the resulting average section length — 100 ÷ 13 ≈ 7.69 ft — so you can see the spacing that actually results from evenly spaced posts.

Pickets are spaced on a repeating pitch: Picket Pitch = Picket Width + Gap. The number of pickets is the length needing boards divided by that pitch, rounded up. Enter the actual face width of your boards rather than the nominal size. For privacy-style fencing installed tight, enter a gap of 0 — no particular gap is universally correct, so the value stays yours to set.

Gate openings reduce the length that needs rails and pickets, so the gate width is subtracted before pickets are counted. Gates are treated as separate purchased or built units; gate infill materials are not estimated. Each gate can also add two boundary posts, and corners may share posts between connected runs. BuildCalcWorks exposes these assumptions as editable options rather than guessing your layout.

When concrete is included, the calculator uses the same geometry as the dedicated Post Hole Concrete Calculator: Concrete = Hole Volume − Embedded Post Volume, multiplied by the calculated number of posts. Bag quantities, weight and volume conversions come from the same shared concrete engine, so the results match that calculator exactly for identical inputs.

BuildCalcWorks estimates material quantities from the dimensions and spacing you enter. Appropriate post spacing, hole depth, post size, fence height, structural details and code requirements depend on the fence design, site conditions and applicable local requirements.

• Spacing, depth and post size stay user inputs
• Gate and corner assumptions are visible and editable
• No structural, frost-depth or code guidance is implied