Fence Calculator – Estimate Panels, Posts, Rails & Concrete

Plan your fence like a pro. Enter your layout and spacing to instantly estimate how many panels, posts, rails, and bags of concrete you need.

Fence material calculator

Gates replace a panel and usually need two gate posts.

Posts & concrete

% extra materials

How this fence calculator works

This fence calculator is designed to be more flexible than most big-box store tools. It supports:

  • Either a single total fence length or multiple segments with corners.
  • Pre-built fence panels or custom board-and-post construction.
  • Gates that replace panels and require extra posts.
  • Concrete volume and bag counts based on footing size.

Key assumptions

  • Panels or bays are laid out end-to-end along the total fence length.
  • There is a post at every panel/bay junction and at each end.
  • Each gate replaces one panel and uses two gate posts.
  • Concrete footings are cylindrical, with diameter and depth you specify.

Formulas used

1. Total fence length

If you enter a single length:

\( L_\text{total} = L_\text{input} \)

If you use multiple segments:

\( L_\text{total} = \sum_{i=1}^{n} L_i \)

2. Number of panels or bays

For pre-built panels:

\( N_\text{panels} = \left\lceil \dfrac{L_\text{total}}{W_\text{panel}} \right\rceil \)

For custom boards with post spacing:

\( N_\text{bays} = \left\lceil \dfrac{L_\text{total}}{S_\text{post}} \right\rceil \)

3. Posts

Line posts (not counting gate posts):

\( N_\text{line posts} = N_\text{bays or panels} + 1 \)

Gate posts:

\( N_\text{gate posts} = 2 \times N_\text{gates} \)

Total posts:

\( N_\text{posts,total} = N_\text{line posts} + N_\text{gate posts} \)

4. Rails (for board fences)

If you enter rails per bay:

\( N_\text{rails} = N_\text{bays} \times R_\text{per bay} \)

5. Boards / pickets (optional)

If you enter board width and want a solid fence (no gaps):

\( N_\text{boards} = \left\lceil \dfrac{L_\text{total}}{W_\text{board}} \right\rceil \)

6. Concrete volume and bags

Footing volume per post (cylinder):

\( V_\text{footing} = \pi \left(\dfrac{D}{2}\right)^2 H \)

where:

  • \( D \) = footing diameter
  • \( H \) = footing depth (embed depth)

Total volume:

\( V_\text{total} = V_\text{footing} \times N_\text{posts,total} \)

Concrete bags (using bag volume \(V_\text{bag}\)):

\( N_\text{bags} = \left\lceil \dfrac{V_\text{total}}{V_\text{bag}} \right\rceil \)

7. Waste / extra allowance

For each item:

\( N_\text{with waste} = \left\lceil N_\text{base} \times \left(1 + \dfrac{p_\text{waste}}{100}\right) \right\rceil \)

Practical tips for planning your fence

Choosing panel width or post spacing

  • 6 ft panels are common for privacy fences and make layout simple.
  • 8 ft post spacing is typical for board fences with 2×4 rails.
  • In windy or high-snow areas, consider shorter spacing (6 ft) for extra strength.

Post depth and footing size

  • A common rule of thumb is to bury 1/3 of the post length in the ground.
  • For a 6 ft tall fence, a 9 ft post with ~3 ft buried is typical in cold climates.
  • Footing diameter is often 3× the post width (e.g., 4×4 post → 12 in hole).

Accounting for gates

  • Each gate usually needs two heavy-duty posts with larger footings.
  • Use stronger hinges and latches on wider gates (10–12 ft drive gates).
  • Consider adding a wheel to support very wide gates and reduce sagging.

FAQ

How much extra material should I order?

For most residential fences, 5–10% extra is enough to cover cutting waste, warped boards, and mistakes. For complex layouts or sloped terrain, 10–15% is safer.

Should I measure in feet or meters?

Use whichever you’re comfortable with. The calculator handles both and converts internally. Just be consistent for each measurement (don’t mix feet and meters in the same field).

Does this calculator handle slopes?

The calculator assumes horizontal runs. On steep slopes you may need more posts and shorter bays. In those cases, break the fence into smaller segments that approximate your terrain.

Can I use this for chain-link or wire fences?

Yes, for posts and concrete it works the same. For fabric or wire rolls, divide the total fence length by the roll length to estimate how many rolls you need.