RediCalc.com
Last updated: June 1, 2026

Fence Calculator: How Many Posts Do You Need?

Calculate exactly how many fence posts, rails, pickets, and concrete bags you need for your fence project. Supports privacy, picket, and board-on-board fence styles.

Fence Details

Fence Materials

Fence Posts15
Rails39
Pickets / Boards234
Concrete Bags (50 lb)30
Fence Sections13
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Understanding the Fence Calculator

A fence calculator estimates the posts, rails, and panels or pickets needed to enclose an area, based on the fence length and style. It helps you plan a fencing project and order the right quantities the first time.

Posts set the framework

Posts are spaced at regular intervals — commonly 6 to 8 feet apart — so the fence length and chosen spacing determine how many you need, plus one extra to finish the run. Corners and gates require additional or heavier posts. Rails and pickets or panels then fill the spans between posts.

Gates and terrain

Remember to plan for gate openings, which interrupt the picket count and need sturdier hardware. Sloped or uneven ground may require stepped or racked panels and can change material needs. Measuring the actual perimeter carefully, including any irregular boundaries, keeps your estimate accurate.

Tips & things to know

  • Space posts evenly, typically 6–8 feet apart.
  • Plan extra heavy-duty posts for corners and gates.
  • Sloped ground may need stepped or racked panels.

How Fence Materials Are Calculated

Posts and pickets are calculated from fence length and spacing:

Posts = (Length / Spacing) + 1 + Gates

Pickets = Pickets per section × Sections

Concrete = 2 bags (50 lb) per post

Example: 100 ft privacy fence, 8 ft spacing → 14 posts, 36 rails, ~264 pickets

Sources

  • Home Builders Association. "Residential Fence Guide."

How to Use the Fence Calculator

1

Open the Fence Calculator

Navigate to the Fence Calculator page on Redicalc. The calculator loads instantly with no sign-up required.

2

Enter your values

Fill in project dimensions, material quantities, or specifications. Toggle between metric and imperial units if available.

3

Review your results

Your fence results appear instantly as you type. Review the breakdown, charts, or detailed analysis provided.

4

Adjust and compare

Try different input values to compare scenarios. This helps you understand how changes affect the outcome.

5

Share or save your results

Use the copy or share buttons to save your results. You can also bookmark the page for quick access later.

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Frequently Asked Questions

How deep should fence posts be?

Posts should be buried 1/3 of their total length. For a 6 ft fence, use 8 ft posts buried 24-30 inches deep.

How many bags of concrete per post?

Two 50-lb bags for a 4x4 post in a 10" diameter hole, 30" deep. Larger posts or deeper holes may need 3-4 bags.

What is the standard post spacing?

8 feet is the most common spacing. Use 6 feet for added strength in high-wind areas or with heavy fence boards.

Do I need a permit for a fence?

Most areas require a permit for fences over 6 feet. Check local zoning for setback requirements, height limits, and HOA restrictions.

How many rails per section?

Privacy fences use 3 rails (top, middle, bottom). Shorter picket fences can use 2 rails. Rails are typically 2x4 lumber.