Concrete bag chart
How many bags a hole or a pad takes, by bag size. Rounded up, because a job half a bag short is a second trip.
| Pour | Cubic feet | 40 lb bags | 60 lb bags | 80 lb bags |
|---|---|---|---|---|
| 10" hole, 3 ft deep | 1.64 | 6 | 4 | 3 |
| 12" hole, 3 ft deep | 2.36 | 8 | 6 | 4 |
| 4" slab, 3 × 3 ft | 3.00 | 10 | 7 | 5 |
| 4" slab, 4 × 4 ft | 5.33 | 18 | 12 | 9 |
| 6" slab, 4 × 4 ft | 8.00 | 27 | 18 | 14 |
Reading it
- A post hole holds less than the whole hole: the post takes up some of it. Subtract the post before you count bags.
- Buy one more bag than the table says. Concrete you did not need is cheaper than a second trip mid-pour.
- These are yields for standard bagged mix, as printed on the bag.
For the case this table does not cover
- Concrete footings and slabs
Cubic yards for a run of post footings or a slab, and the bags of ready-mix that buys.
- Fence post spacing
Post count and the actual on-centre spacing for any run and maximum span.