Fence Post Spacing Calculator
Calculate fence post spacing, number of posts needed, and materials for any fence length.
Supports metric and imperial units.
Correct fence post spacing is critical for a strong, stable fence. Posts that are too far apart will cause the fence to sag and flex; posts that are too close waste materials and labour. The standard approach is to decide on a panel or rail span first, then calculate how many posts fit your total fence length.
The Basic Formula
Number of posts = (Fence length ÷ Post spacing) + 1
The “+1” accounts for the final end post. For example, a 20-metre fence with 2-metre spacing needs 20 ÷ 2 = 10 spans, so 11 posts.
Standard Post Spacing by Fence Type
| Fence Type | Metric Spacing | Imperial Spacing |
|---|---|---|
| Picket fence | 1.2 – 1.8 m | 4 – 6 ft |
| Privacy fence | 1.8 – 2.4 m | 6 – 8 ft |
| Split rail | 2.4 – 3.0 m | 8 – 10 ft |
| Chain link | 3.0 m | 10 ft |
| Farm / wire | 2.4 – 3.6 m | 8 – 12 ft |
Post Depth (Setting Depth)
A post should be buried to at least one-third of its total length. A common rule: set posts 600 mm (2 ft) deep for a 1.2 m (4 ft) fence, and 900 mm (3 ft) deep for a 1.8 m (6 ft) fence. In cold climates, post bases should be set below the frost line to prevent heaving.
Concrete per Post
Each post typically requires one 20 kg (40 lb) bag of fast-setting concrete, or a larger post in heavy soil may need two bags. This calculator estimates bags based on a standard hole size of 200 mm (8 in) diameter.
Corner and Gate Posts
Corner posts and gate posts experience much higher loads. These should be set deeper (add 150–300 mm / 6–12 in) and use a larger diameter hole. Always double up posts on both sides of a gate.
Practical Tips
- String a line between end posts before digging to keep posts aligned.
- Rent a post-hole auger for more than 10 posts — it saves significant effort.
- Allow concrete to cure at least 24–48 hours before attaching fencing.
- Check local bylaws — many areas have height limits and setback requirements for fences.
This calculator gives you an accurate estimate for planning materials and budgeting your fencing project.
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
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