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.