Excavation
Excavator Reach and Dig Depth by Size: Will It Reach (Oregon)
Cojo
June 19, 2026
6 min read
Excavator dig depth by size is the number that decides whether a machine can actually reach your work in one pass. Each class of excavator has a realistic maximum dig depth and horizontal reach, and those two numbers determine whether the machine can hit basement or footing depth, or stretch into a back-corner trench without repositioning. A mini handles shallow drains and trenches; a mid-size handles foundations and deeper utilities; a full-size reaches deep cuts and long arms. Matching the machine class to your required depth and reach up front avoids the worst outcome on a dig: bringing a machine that physically cannot get to the work.
Two measurements describe what an excavator can touch. Maximum dig depth is how far below grade the bucket can reach. Maximum reach is how far out horizontally the machine can dig from where it sits.
These matter because they set hard limits. If a footing has to go to frost depth and the machine tops out shallower, it cannot finish the cut. If a trench runs to the back corner of a lot and the machine cannot reach it from accessible ground, you either move the machine repeatedly or you bring a bigger arm. Getting this right is the core of picking equipment, which is why our excavation equipment guide and excavator size classes explained both start here.
These are general planning ranges by class. Exact numbers vary by make, model, and arm configuration, so treat the table as a map, not a spec sheet. Always confirm the figures for the specific machine.
| Class | Typical max dig depth (planning range) | Typical horizontal reach (planning range) |
|---|---|---|
| Mini (compact, around 1-2 ton) | About 6 to 9 ft | About 10 to 15 ft |
| Small / midi (around 3-6 ton) | About 8 to 13 ft | About 15 to 21 ft |
| Mid-size standard (around 8-15 ton) | About 12 to 18 ft | About 20 to 28 ft |
| Full-size (around 18-25+ ton) | About 18 to 24+ ft | About 28 to 35+ ft |
The depth your dig needs is driven by what you are building and by Oregon conditions:
The colder, the wetter, or the deeper the service, the more depth you need, which pushes you up the machine-class ladder. The broad Oregon excavation contractor guide ties these conditions together across topics.
Machine size drives the hourly rate, so reach and depth are also a cost decision. Industry Baseline Range: an excavator plus operator runs $150 - $350+ per hour, with the mini at the low end and a full-size machine at the high end, plus a $250 - $800+ mobilization fee to get it to site. These are industry baseline ranges for planning only -- actual pricing depends on site conditions, soil, access, depth, haul-off, and current market conditions. Get a site-specific quote. Renting a machine that is too small and grinding away slowly often costs more than the right machine doing the job in fewer hours.
The frustrating part of matching a machine is that reach and access pull against each other. The machine with the reach you want may be too wide or heavy for your gate, your soft yard, or your tight side-setback. The machine that fits may not reach the far corner or the required depth.
When that happens, contractors solve it with technique, not just a bigger machine: digging from multiple setups, using an extended or long-reach arm, or planning the access route so the machine can get close enough to the work. The point is to know the numbers before the machine shows up, not after.
The patterns we see when machine size is guessed instead of matched:
Specs on a chart are one thing; what they mean on your site is another. A few common Oregon scenarios show how dig depth and reach drive the machine choice.
A footing or foundation drain in the Willamette Valley often sits in the range a small or mid-size machine reaches comfortably, but a deep foundation drain meant to keep water well below a basement can push toward the deeper end, especially when the trench also has to maintain fall over a run. A utility trench to a back-of-property well or outbuilding is usually a reach problem before it is a depth problem, the machine has to stretch across the yard or reposition repeatedly. A basement excavation is squarely a depth job that rules out the smaller classes.
The other factor the chart does not show is that maximum dig depth and maximum reach are not achieved at the same time. A machine hits its deepest point digging more or less straight down, and its farthest point digging out and shallow. The usable working envelope is the area in between, which is smaller than either single number suggests. That is why an experienced operator plans where the machine sits for each part of the work, so the bucket reaches the whole dig without the machine having to be picked up and moved more than necessary.
Reading the job this way, depth here, reach there, and the working envelope in between, is how a contractor picks one machine that does the whole job in a single mobilization instead of discovering mid-dig that the chosen machine cannot finish.
Excavator dig depth and reach by size are the numbers that decide whether a machine can do your job. Map your required depth, set by what you are building and by Oregon's frost and water conditions, to the class that can reach it, then check that machine can actually access the site. Cojo sizes the right machine to the job across Oregon so the dig gets done in one mobilization. See our excavation services or request a free estimate to get the right equipment matched to your site.
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