# Free online fence calculator

> A fence estimate starts with post spacing and works out from there. Enter your fence length, height, style, and gate count to get posts, rails, pickets or rolls, and the concrete.

Calculate posts, rails, pickets, concrete bags, and chain-link rolls for any fence — with gate count, post spacing, and waste factor.

**Interactive version:** https://onlinecalculator.me/construction/fence/
**Category:** Construction

## How to use

1. Enter total fence length and height in feet.
2. Set your post spacing (8 ft is standard).
3. Enter the number of gates.
4. Choose your fence type.
5. Read posts, concrete, rails, pickets or rolls, and gate posts.

## Formulas

```
postsNeeded    = ceil(fenceLength / postSpacing) + 1
gatePostsNeeded= gateCount × 2
concreteBags   = ceil((postsNeeded + gatePostsNeeded) × 0.5)

Privacy / Picket:
  railsPerSpan = ceil(fenceHeight / 2)
  spans        = ceil(fenceLength / postSpacing)
  rails        = ceil(spans × railsPerSpan × wasteMultiplier)
  pickets      = ceil(fenceLength × 3 × wasteMultiplier)

Split-rail:
  railsPerSpan = 2 (height ≤ 3 ft) or 3 (taller)
  rails        = ceil(spans × railsPerSpan × wasteMultiplier)

Chain-link:
  rolls = ceil(fenceLength × wasteMultiplier / 50)
```

## Worked example

150-ft privacy fence, 6-ft height, 8-ft post spacing, 1 gate, 10% waste:

```
postsNeeded    = ceil(150/8) + 1 = 19 + 1 = 20
gatePostsNeeded= 1 × 2 = 2
concreteBags   = ceil(22 × 0.5) = 11 bags

railsPerSpan   = ceil(6/2) = 3
spans          = ceil(150/8) = 19
rails          = ceil(19 × 3 × 1.10) = 63 rails

pickets        = ceil(150 × 3 × 1.10) = 495 pickets
```

## Notes

- Set posts 1/3 to 1/2 their total length into the ground — a 9-ft post gives 6 ft above grade.
- In frost-heave regions, bury posts below the frost line (typically 42–48 in in the northern US).
- Gate posts need to be at least one size larger than line posts to handle the swing load.

## Frequently asked questions

### How many fence posts do I need?

Divide your fence length by the post spacing and add one for the end post. For example, a 150-foot fence at 8-foot spacing needs ceil(150/8) + 1 = 20 posts. Add 2 extra posts per gate.

### How much concrete do I need per post?

A common estimate is half a 50-pound bag of concrete per post for standard 4×4 posts set in 8-inch-diameter holes about 2 feet deep. Double this for larger posts or taller fences in loose soil.

### How many pickets per linear foot of fence?

Standard 3.5-inch pickets with a 0.5-inch gap take up 4 inches of total space per picket, giving 3 pickets per linear foot. A privacy fence uses a similar calculation with boards butted tight together (no gap) — about 3.5 pickets per foot.

### What is the best post spacing for a fence?

8 feet is the most common residential post spacing. It matches standard panel widths and keeps posts from needing extra bracing. Some manufacturers make pre-built panels at exactly 8 feet wide to fit this spacing.

### How is chain-link fence measured?

Chain-link fabric comes in rolls, typically 50 linear feet per roll. Multiply your fence length by the waste factor and divide by 50. You order posts and top rails separately by linear foot.

### How do I share my fence calculation?

Click Share for the plain page URL, or Share with my numbers to encode your fence dimensions in the URL.

## Sources

- [Fence (posts, rails, boundary structure)](https://en.wikipedia.org/wiki/Fence) — Wikipedia
- [Perimeter (length of a boundary)](https://en.wikipedia.org/wiki/Perimeter) — Wikipedia

## Related calculators

- [Concrete calculator](https://onlinecalculator.me/construction/concrete/) — Calculate bags or yards of concrete for the post footings.
- [Lumber calculator](https://onlinecalculator.me/construction/lumber/) — Estimate lumber board feet for fence rails and stringers.
- [Gravel calculator](https://onlinecalculator.me/construction/gravel/) — Calculate gravel for drainage around fence posts.
- [Square footage calculator](https://onlinecalculator.me/construction/square-footage/) — Measure yard area for planning fence runs and gates.
- [Paint calculator](https://onlinecalculator.me/construction/paint/) — Estimate paint or stain for your finished fence.

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Machine-readable index: https://onlinecalculator.me/llms.txt