Fence Post Concrete Calculator

How to calculate

The hole is round and the post is square. Concrete-filled depth excludes any gravel below the concrete. The post is assumed to occupy the full concrete depth. Bags round up across the whole project.

Worked example

Number of posts: 10 · Round hole diameter (in): 12 · Square post actual width (in): 3.5 · Concrete-filled depth (in): 24 · Bag yield (cu ft): 0.6 · Extra material (%): 10.

These inputs produce 26 concrete bags. Change the measurements above to match your project.

Before you order

Confirm hole dimensions and embedment for your site and fence. A 0.6 cu ft bag yield is a common 80 lb concrete example; check your exact mix.

For an irregular footprint, split the project into rectangles. Calculate each section and combine unrounded quantities before rounding the final order. Ask the supplier to confirm product yield and available package sizes.

Common questions