What auger diameter should you choose?
The hole should be wide enough for the post, concrete, and adjustment room. Larger bits need more torque and more stable carrier weight, especially in clay or rocky soil.
| Auger diameter | Common use | Machine note |
|---|---|---|
| 6 inch | Small fence posts, signs, light planting | Easy for compact machines |
| 9-12 inch | Fence posts, deck supports, general holes | Most common utility range |
| 18 inch | Trees, larger posts, small footings | Needs more torque and stability |
| 24 inch | Large planting holes and footings | Confirm flow and carrier rating |
What soil changes the decision?
- Clay needs more torque and slower drilling.
- Rocky ground may require pilot holes or a different tool.
- Wet soil can collapse after drilling; plan concrete timing.
- Frozen ground increases wear and may exceed small-machine limits.