How this fence post calculator works
Fence posts are spaced evenly along the run. The number of posts is the fence length divided by the spacing, rounded up, plus one end post. Each post hole is a cylinder, so its volume is π × radius² × depth; the calculator uses the hole diameter and depth you enter, multiplies by the number of posts and converts the total to 80 lb bags (about 0.6 cubic feet per bag).
Spacing depends on the fence type: about 8 feet for most wood privacy fences, 6 feet for heavy panels, and up to 10 feet for wire or welded-wire fencing. A wider or deeper hole is always the safer choice in soft soil or on windy, exposed sites.
Fence building tips
- Set corner and end posts in concrete first; they carry the most load.
- Gradual line and level: run a string line before setting posts.
- Increase depth for frost protection (rule: half the frost depth below ground).