How Deep Can a Skid Steer Auger Attachment Really Dig?

If you’ve ever drilled post or utility holes with a skid steer, you’ve probably wondered how far you can really go before the auger maxes out. The short answer: it depends on your setup. We know, boring and vague (but true!) answer.

We make attachments, though, so we may as well use our own as a more specific example. With a Prime Attachments Earth Auger, you’re looking at about 48 inches deep with a standard bit, and up to 72 inches or more with an extension. That’s deep enough for most fence posts, sign bases, footing holes, and even telephone poles (a standard 40-foot pole is buried 6 feet deep). It’s also easily deep enough to plant shrubs or young trees. 

The beauty of doing your augering with a skid steer is that you don’t even need to swap machines or call in an excavator. Let’s “dig” into the details.

Standard Depth and Extensions

Most skid steer auger attachments use a 4-foot (48") auger bit as standard. You won’t see many sold in lengths much greater because 4 feet is plenty for skid-steer appropriate digging tasks like typical Midwest frost lines, post holes, and foundation prep. That rule of thumb is what guided the heavy-duty design of the Prime Attachments auger, which handles that depth with power to spare.

But when you need to go deeper — say, for deep drainage systems, big commercial footing piles, or those telephone poles we mentioned — our 24-inch extensions give you the reach without sacrificing stability. Oh, and if you’re drilling deep, remember that the longer the auger, the more torque your machine will need to stay efficient. Our planetary gearbox direct drive setup delivers that torque to keep rotation steady and clean, even in dense soil.

It’s Not Just the Length of the Auger Bit, But How You Use It

Even with the right length auger bit, real-world digging depth depends on a few key factors:

• Soil Type: Dense clay, frozen ground, or rocky soil will slow progress or stop it altogether without high torque and sharp bits.
• Moisture and Compaction: Dry, compacted earth resists more than moist soil — but then again, overly wet ground can collapse back in, which also is a no go.
• Bit Size: Wider bits (like 18” or 24”) move more material, but limit how deep you can go before you start bogging down.
• Machine Flow and Pressure: For the Prime Attachments auger, the ideal range is 15-25 GPM hydraulic flow at up to 3,000 PSI for peak performance.

In other words, bit length is just part of the picture. Torque is the real limiter. It takes a high-torque auger skid steer attachment equipped for 3,000 PSI to handle 6-foot drilling depth and 2-foot width with standard extensions and no loss of rotation speed. 

Auger vs. Backhoe: Which Skid Steer Auger Attachment for Deep Digs?

For straight vertical holes like posts, piers, ball-rooted trees, or fence lines, an auger for skid steers wins every time. It’s fast, it’s precise, and the smaller vehicle minimizes surface disruption.

With that said, if your skid steer project calls for trenching, running utility lines, or deep, wide-footed holes, a backhoe attachment will likely give more control and efficiency at deeper angles. Augers dig clean, narrow holes; backhoes move bulk earth. Feel free to compare them, but for most contractors, having both means you can cover 95% of excavation jobs with one skid steer and two attachments.

How Do You Keep Auger Holes Straight and Clean?

Going deep is one thing. Staying straight is another. Here’s a few field-tested habits that can help:

• Start slow to establish a vertical pilot.
• Avoid full throttle in the first few inches — that’s when drift starts!
• On slopes, set your machine square to gravity, not the terrain.
• Periodically lift the auger to clear spoils and prevent clogging.

These best practices set you up to succeed. Still, we do everything we can to help you out with a heavy-duty post hole auger design, too. Our Earth Auger attachment features a 2" hex drive for stability and greasable pivot points to keep it centered and durable during repeated use. Add the self-centering frame, and you’ll notice cleaner starts and straighter holes every time.

The Bottom Line

So…how deep can a skid steer auger really dig?

About four feet standard, six feet with extensions, and as deep as your torque and soil will let you.

Luckily, that’s the perfect range for contractors like fence builders and sign installers. Even if you mainly handle high-volume commercial jobs or challenging tasks like drilling through compacted fill or frost, a heavy-duty post hole auger setup gets it done. The added gearbox torque and reinforced frame of the Prime Earth Auger reduces your flex and vibration, so you get smoother operation even when ground conditions are nasty. You’re drilling clean, straight, and strong. 

When you’re ready to see what your skid steer can really do, request a quote or check out the full lineup of attachments that take your machine from good to downright badass!