Home Improvement
Fence Post Calculator
Enter fence length and spacing to see posts and panels needed.
How many fence posts?
A straight fence run needs a post at each end, so posts equal the number of spacing gaps plus one: floor(length ÷ spacing) + 1. Panels between posts are roughly posts minus one when every bay is a full panel. Enter the run length along the ground and the centre-to-centre spacing your panel or rail system uses — often about 1.8 m for standard panels. Corners, gate posts, end posts on a change of direction and stepped slopes need extras you must add by hand. Fixing method (concrete-in versus spike) does not change how many posts you buy. For panel-first take-offs see the companion fence panel calculator, and for layout area the garden area tool.
Worked example
A 20 m run at 1.8 m spacing → floor(20 ÷ 1.8) + 1 = 12 posts and about 11 panels. At £12 per post, posts alone ≈ £144.
Limits and assumptions
Models a single straight run. Gates, corners, gravel boards and slope stepping are not automatic.
Frequently asked questions
Should spacing match panel width?
For most panel systems, yes — use the manufacturer bay width as spacing.
Do gravel boards change post count?
Usually no; they sit under panels. Post count still follows bay spacing along the run.
Concrete-in or meta-spike — does it matter here?
Only for installation cost and depth. Quantity of posts is the same.
How do slopes affect the count?
Measure along the ground and expect extra posts where the fence steps — the flat formula under-counts stepped lines.