Pine Tools Hub

Fence Calculator

Calculate the number of posts, pickets, rails, and concrete bags needed for your fence.

Fence Details

Settings

Estimation Results

Posts Needed (inc. gate posts)0 posts
Rails Needed0 rails
Pickets0
Concrete Bags (80lb)0 bags

For estimation purposes only. Verify material quantities with your fence supplier before purchasing.

How This Calculator Works

The fence calculator uses standard construction geometry to estimate materials. The number of posts is calculated by dividing total length by post spacing, then adding 1 (for the end post), plus any extra posts needed for gates.

The formula for pickets is: (Total Length × 12 inches) ÷ Picket Width.

For concrete, we assume a standard 10-inch diameter hole that is 24 inches deep. This requires roughly 0.6 cubic feet of concrete, which is exactly one 80lb bag per hole. We apply a standard 10% waste factor to wood materials.

Example Calculation

For a 100 foot privacy fence with 8-foot post spacing, using 5.5-inch pickets and 3 rails:

  • Number of Sections: 100 ÷ 8 = 12.5 (rounds up to 13)
  • Number of Posts: 13 + 1 = 14 posts
  • Rails Required: 13 sections × 3 rails = 39 rails
  • Pickets Required: (100 × 12) ÷ 5.5 = 218 pickets
  • Concrete Bags: 14 holes × 1 bag/hole = 14 bags (80lb)
  • With 10% waste: buy 43 rails and 240 pickets.

Common Fence Lengths (8ft Spacing, Privacy Pickets)

Fence LengthPosts / Concrete Bags2x4 Rails (3-rail)5.5" Pickets (+10% waste)
50 ft8 posts24 rails120 pickets
100 ft14 posts42 rails240 pickets
150 ft20 posts60 rails360 pickets
200 ft26 posts78 rails480 pickets

Fence Building FAQs

How many bags of concrete per fence post?
For a standard 4x4 fence post set in a 10-inch diameter hole that is 2 feet deep, you need about 1 bag of 80lb concrete. For a larger 6x6 post or a deeper hole, you may need 1.5 to 2 bags per post.
How far apart should fence posts be?
Standard fence posts are usually spaced 8 feet apart (on center). If you are building a very tall or heavy fence, or live in a high-wind area, you may want to space them 6 feet apart instead.
How deep should fence post holes be?
A general rule of thumb is to bury one-third of the post underground. For a 6-foot fence, you will need a 9-foot post with 3 feet buried in the ground. You must also dig below your local frost line to prevent heaving.
How many pickets do I need for a 100 ft fence?
Using standard 5-1/2 inch wide pickets installed side-by-side (privacy fence) with no gap, you need about 2.18 pickets per foot. For a 100-foot fence, that equals roughly 218 pickets. Our calculator adds a 10% waste factor, bringing the total to about 240 pickets.
How many rails do I need for a fence?
Fences up to 4 feet tall generally need 2 horizontal rails. Fences 5 feet to 8 feet tall require 3 horizontal rails to prevent the pickets from warping.

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Reviewed & verified by Ketan Chandore

Technology creator and founder of Pine Tools Hub · Last updated: June 2026