Forstner vs. Auger Bit: Which One to Use?

Forstner vs. Auger Bit: Which One to Use?

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If you plan on working with wood, something you are going to need is a good drill along with a  whole bunch of drill bits. Now, there are of course dozens of different kinds of drill bits out there, each of which is designed for its own specific purpose.

Today, we are here to look at two specific types – Forstner and auger bits. Neither of these is your average drill bit, and both look very particular. Let’s figure out what their purposes are, and what the differences between them are.

Forstner and Auger Bits: The Basics

Before we get into talking about the differences between these two types of drill bits and what they are ideal for, it is probably a good idea to figure out what exactly both of these drill bits are.

What Is a Forstner Bit?

Forstner Bit OK, so the technical definition of a Forstner bit is a spurless wood drilling bit used especially for drilling blind holes. The defining feature of a Forstner drill bit is the fact that it has the ability to drill a flat-bottomed hole as opposed to normal drill bits, which create a pointed hole.

For this reason, Forstner bits are often used for hardware installations where achieving a precise mortise depth is required. Not only are Forstner bits used to create flat-bottom holes, but also for drilling angled holes, holes that overlap, or holes that appear on the edge of a material.

What also needs to be noted is that Forstner bits have a very long shank, but most of it is not spiraled or grooved. On a normal drill bit, the entire shank features that spiral design, a thread, so to speak, thus transferring that spiraling into wood and allowing for screws to hold securely. Forstner drill bits do not create this threaded spiral design in the wood, but instead produce holes that are flat, smooth, and straight on the inside.

The very important thing to note is that due to the force required to make cuts with the Forstner bit, it is generally used with drill presses or with braces and not just with regular power drills. That said, you may use Forstner bits in a hand drill, but it won’t be easy to do. These drill bits have a tendency to walk or to drift away from the center of the cut, especially at the beginning when the cut is being made.

To learn how to use these properly, check this article.

What Is an Auger Bit?

Auger Bit The first thing that you need to know about augers in general is the fact that they were first invented to transport very difficult to transport materials. Originally augers looked like very long screws that twisted in an upward direction, transferring whatever material from bottom to top. These were often used to transport things like water.

The reason why augers are so efficient at transporting things like water, sand, and other such materials is due to their shape, which is designed to pull the material out of a certain space or a hole. Therefore, based on the original auger, the auger drill bit was invented. The auger drill bit is designed to drill very deep holes with the aim of removing all of the material that it cuts loose. In other words, this type of drill bit excels at removing the wood shavings from a hole, thus leaving it clean and ready to work with.

Auger drill bits may be used in drill presses, but due to their nature, they are quite easy to use in a handheld power drill as well. Due to the functionality of auger drill bits, they are often used to drill holes in very thick and tough timber such as decking materials. They are also often used to drill holes for cables and pipes in between walls and in between floors.

Do keep in mind that there is also a much larger version of the auger drill bit known as the earth auger, which is designed to drill large holes into the ground with the aim of inserting posts and other such objects.

Forstner Bit vs. Auger Bit: What Are the Differences?

Alright, so now that we know what both Forstner and auger drill bits are, let’s take a quick look at the main differences between them.

1. Length

One of the main differences between these two types of drill bits has to do with their length, with the auger drill bit usually being the much longer of the two.

Yes, both drill bits come in a variety of lengths, but generally speaking, the Forstner drill bit is going to top out at around 3-7/8-inches, whereas auger drill bits can be several feet long. Auger drill bits are designed for deep drilling purposes, whereas Forstner drill bits are not.

2. Material Removal

As mentioned above, auger bits are specially designed to drill very deep holes while removing all of the material that they cut loose. This makes them ideal for applications that require smooth, straight, and clean holes.

Forstner bits, on the other hand, while they do remove some of the material from the hole, do not remove all of it. If you need clear holes that are free of sawdust and wood shavings, then it’s an auger bit that you need to go with.

3. Tool Compatibility and Ease of Use

Another major difference between these two drill bits is the fact that auger bits are quite a bit easier to use and are also compatible with a wider variety of tools. The simple fact is that augers can be manual, you can put auger bits in power drills and drill presses, and you can have full-sized earth augers as well.

On the other hand, while Forstner bits may be used in handheld power drills, they are really only ideal for drill presses. Forstner bits require a whole lot of force to begin making that cut, and they often go off-center as well, therefore, requiring more accuracy and skill to use.

4. Main Applications

The main difference between these two drill bits of course has to do with the applications that they are designed for. When it comes down to it, Forstner bits are designed to drill clean and clear flat-bottomed holes with the main purpose being for hardware installation.

Auger bits, on the other hand, are designed to drill very deep and long holes, generally with the purpose of hollowing out an area for things like inserting cables and pipes. Auger bits may also be used to simply drill holes for the insertion of fence posts or other such purposes.

Which of the Two Should You Use?

As you can see, both of these drill bits have very different applications, and therefore which one you choose completely depends on the application at hand.

For drilling deep and long holes into hard materials, an auger bit is the better choice, particularly if you need to ensure that all the sawdust in wood shavings are removed in an efficient manner. On the other hand, if you are attaching pieces of wood together, installing hardware or you need any sort of flat-bottomed hole for any purpose, then it is the Forstner drill bit that you need.


There you have it folks, everything you need to know about Forstner and auger drill bits. Let’s face it, people. If you are serious about carpentry and woodworking, then chances are that you are going to need both of these drill bits.

I wrote about my favorite Forstner bit sets here.

How Do Forstner and Auger Bits Compare with Other Tools?

See how Forstner bits compare with: routers | spade bits and hole saws

See how auger bits compare with: spade bits