Dig Depth, Reach and Dump Height: The Three Numbers That Decide the Job
Maximum dig depth is the headline figure, but reach and dump height decide whether you can load a trailer or dig a footing from where the machine is parked.
Spec sheets quote three working-envelope figures. Each one answers a different question about the job in front of you.
Maximum dig depth
The deepest point the bucket teeth can reach with the tracks on level ground. Rippa's 1 to 1.5 tonne machines dig around 1.8 m; the R18 PRO reaches 2,420 mm and the R22 PRO 2,365 mm; the R57 PRO reaches 5,780 mm.
Two things get missed:
- Maximum depth is directly below the machine at full stretch. A trench you can dig cleanly is usually 300 to 500 mm shallower than the maximum, because you need the bucket to curl and the dipper to work at an angle.
- Blade position matters. Digging over the blade adds stability; digging with the blade behind you is less stable but gives a little more depth.
For a Perth pool dig of 1.6 to 1.8 m, that means a 1.8 to 2 tonne machine, not a 1 tonne, unless you are happy to bench the excavation and reposition.
Reach at ground level
How far from the swing centre the bucket teeth reach with the bucket flat on the ground. Reach decides how many times you move the machine to dig a footing along a wall, and whether you can dig a trench from the driveway without tracking over the lawn. As a rule, reach is around 1.6 to 1.8 times the dig depth on compact machines.
Dump height
The height of the bucket pivot when the boom is raised and the bucket is curled to empty. It tells you what you can load into. Rippa's 1 to 2 tonne excavators sit between 2.2 and 2.3 m, which is enough for a plant trailer or a tipper ute tray but not a high-sided truck. Loading a truck is a job for the R32 PRO and up, or for a skid steer with a high-dump bucket.
Putting the three together
| Job | Depth needed | What matters most |
|---|---|---|
| Reticulation and cable trench | 300–450 mm | Reach, so you dig long runs without moving |
| Footings for a retaining wall | 400–600 mm | Reach along the wall line |
| Soakwells (Perth stormwater) | 1.2–1.8 m | Dig depth |
| Pool shell | 1.6–2.0 m | Dig depth and dump height to clear spoil |
| Farm dam or soak clean-out | 2.5 m + | Dig depth and reach from the bank |
Where Rippa models land
The comparison table lists dig depth for each excavator, and the machine finder weights it against your access and towing. If the job needs more depth than your access allows, benching the excavation or hiring a bigger machine for a day is usually cheaper than buying one you cannot get onto the site.