Calculator
Fence Post Calculator
Work out posts, panels, rails and concrete bags for your fence run.
Model reviewed August 2026
Posts needed
26 posts
25 sections at 8 ft spacing
- Panels / sections
- 25
- Rails
- 75
- Concrete bags (50 lb)
- 78 bags
- Estimated concrete weight
- 3,900 lb
Estimates only. Local pricing, site conditions and code requirements change the real number.
The formula
Posts = (length / spacing) + 1; Concrete per post = hole volume - post volume
Post holes should be about one-third of the post height deep and three times the post width wide. High-wind and frost-prone jurisdictions often require deeper setting for 6 ft and taller fences.
Worked example
A 200 ft fence at 8 ft spacing needs 26 posts, 25 panels and about 78 bags of 50 lb concrete at three bags per post.
Frequently asked questions
How deep should fence posts be?
Set posts one-third of the above-ground height deep, so a 6 ft fence uses a 2 ft hole minimum. High-wind jurisdictions often require 2.5 to 3 ft, and cold-climate jurisdictions require footings below the local frost line.
How many bags of concrete per fence post?
Two to three 50 lb bags per post for a 4x4 in a 10-inch hole; three to four bags for a 6x6 or a deeper hole.
Sources
Sources & verification
- International Residential Code — barrier and post requirements
- AWPA treated-wood use categories
- International Code Council (IRC/IBC)
Model vintage August 2026. The links above are the issuing agencies' own pages — we publish them so you can confirm the current rule yourself, not as evidence that each fact on this page was re-checked with them today. Cost figures are modeled estimates based on national baselines adjusted for local labor and material pricing, not quotes. Permit rules change; confirm with the building department before starting work.