Concrete bags per post chart
| Hole size | Concrete volume | 40 lb bags | 60 lb bags | 80 lb bags |
|---|---|---|---|---|
| 8 in × 24 in | 0.70 ft³ | 3 | 2 | 2 |
| 8 in × 36 in | 1.05 ft³ | 4 | 3 | 2 |
| 10 in × 24 in | 1.09 ft³ | 4 | 3 | 2 |
| 10 in × 36 in | 1.64 ft³ | 6 | 4 | 3 |
| 12 in × 24 in | 1.57 ft³ | 6 | 4 | 3 |
| 12 in × 36 in | 2.36 ft³ | 8 | 6 | 4 |
| 12 in × 48 in | 3.14 ft³ | 11 | 7 | 6 |
| 14 in × 36 in | 3.21 ft³ | 11 | 8 | 6 |
| 16 in × 36 in | 4.19 ft³ | 14 | 10 | 7 |
Bag yields are planning assumptions and can vary by product. Always use the yield printed on the concrete mix you purchase.
Example: 12-inch hole, 36 inches deep
A cylindrical hole 12 inches in diameter and 36 inches deep has about 2.36 cubic feet of volume before accounting for the volume occupied by the post itself. Using the conservative full-hole method shown here, that rounds up to about 4 × 80 lb bags, 6 × 60 lb bags or 8 × 40 lb bags.
Calculate your actual posts
Enter your hole diameter, concrete depth, number of posts and extra-material allowance.
Open Fence Post Concrete Calculator →Why your real quantity can differ
The post itself displaces some concrete, while irregular or over-dug holes can use more. Hole dimensions should be selected for the fence, soil, frost conditions and local requirements—not from this bag-count chart alone.
Planning an entire fence? The BuildGauge Fence Calculator estimates posts, rails, pickets, gates, concrete and fasteners together.