What Is Arbor Size on a Circular Saw and Why Does It Matter? (Covering the 4 Most Common)

The foremost feature of a circular saw is certainly the blade it holds. If the spindle on the saw fails to securely attach the blade to the tool, it will lose the purpose of the saw.

Arbor size is the shaft measurement of a circular saw that holds or supports the hole in the middle of the blade. This diameter determines whether a blade is suitable for a particular circular saw.

While buying a new blade for your circular saw, you must check whether the blade has a compatible arbor size. To learn more about this, carry on reading.

What Is Arbor Size On A Circular Saw

What Is Arbor Size On A Circular Saw?

The blade of a circular saw is mounted at the saw shaft spindle. The shaft of the circular saw that securely attaches the air gap of a blade is known as the arbor. In gist, the size of the shaftthat holds the hole of the blade isthe arbor size of the circular saw blade.

You may wonder why such a tiny shaft is of such great importance. The truth is the shaft will determine the attachment of the blade to the spindle. You know the risk of the circular saw blade slipping due to the wrong set of tension in the spindle and blade. A wrong understanding of the arbor contributes mostly to the blade slipping.

When you are opting for a new kind of blade, there are two things you must consider greatly. The size of the blade and the arbor size. Without a correct and compatible arbor size, the blade will not adjust properly to the blade. You would have to either replace the blade to fit on the circular saw or replace the circular saw to accommodate the blade.

Standard Arbor Sizes For A Circular Saw

Not so coincidently, the arbor size is directly linked to the size of a blade. So, usually, a larger size blade will have a larger arbor size and vice versa. The arbor size and blade size are proportional to each other.

But you can’t ignore one size by wrapping it up the other size. There are some standard sizes suitable for arbors and most of the blades. Let’s find out what those are.

a) 1/4 Inch Arbor Hole Size

This is the shortest and smallest arbor hole available in the market. The blade size of this arbor is 3 inches circular saw blades. As you can see, the blade is quite small, considering the other circular saw blades. Hence, the arbor size is equidistantly smaller.

b) 1/2 Inch Arbor Hole Size

Similar to the ¼ inch arbor, this ½ inch arbor accommodates its proportional blade. The standard blade size for this arbor hole is 6 inches. So, in short, you are getting a double arbor size of the previous one for the double-sized blade. This is a standard arbor size but not that popular.

c) 5/8 Inch Arbor Hole Size

This is one of the most popular and most used arbor holes available in most of the circular saws. Unlike the previous options, this arbor size accommodates more than one circular saw blade size. You can find the same 5/8 inch arbor hole in 7-1/4 to 10 inches blades.

d) 1 Inch Arbor Hole Size

This is the largest arbor size available for circular saw blades. Alike the 5/8 inch hole, this arbor also supports various sizes of blades. From 12 inches to 16 inches, all blades are covered with this 1-inch arbor hole size. After 5/8, this arbor size is widely used by construction folks.

How To Know The Arbor Size Of A Blade?

It would be irrational to guess the arbor size considering the size of the blade the circular saw can accommodate. The arbor size and the blade size can be out of the usual rule, and a manufacturer can have their own policy to determine the arbor and bore size. So, you should know how to measure the arbor size of the circular saw before buying a blade.

1. Measure Via A Circular Saw

If you have your circular saw, you can measure the size with a ruler or tape measure. To measure the outside diameter of the arbor, find the mounting holes of two blades on a circular saw and calculate the distance of the center.

2. Measure Via A Circular Saw Blade

If you have a saw blade that goes perfectly with the circular saw, you can measure the inside diameter with the help of a caliper. If you are not sure about the hole size, you can take the blade to the shop, and they can measure the diameter to select the correct blade.

Some Tips To Remember

  • The size of the blade, the bore size, and the arbor size are proportional to each other. If one variant gets larger, the others will follow and pursue.
  • Arbor size can also refer to the power of a particular circular saw. A bigger arbor size means that the saw has more power and torque. A larger spindle also indicates that.
  • There is no universal rule that each blade will come with a similar arbor size. Depending on the model, the arbor size and the blade size can differ.
  • Blades that are smaller than 12 inches can have a diamond arbor or a 1-inch arbor to it. The extra space between an arbor and the hole is taken up by the reduction bushing.
  • The reduction bushing or rings usually come with a circular saw pack so that you can use a larger hole blade for a smaller circular saw shaft.

People Also Ask


Is the arbor and bore size the same?

The difference between the arbor and bore size is more than the A at the front. Arbor size indicates the shaft of the circular saw that holds the blade. Meanwhile, bore size is basically the size of the hole at the center of the blade.

The basic difference is one that holds and one that attaches. The arbor size can be denoted by the shaft of a circular saw, and the bore size can be denoted by the blade. Are the sizes the same? Well, the bore size is insignificantly smaller than the arbor, so it can penetrate through the arbor but attaches tightly.

How to adjust a small arborsize to a large blade?

What if the blade center, i.e., the bore size, is bigger than the shaft of the circular saw? You don’t have to replace the blade or the saw because you can use a circular saw arbor adapter. And this adapter will attach to the shaft of the circular saw.

Adapters have two types. One type of adapter fits over the shaft to easily switch one size blade to another. On the other hand, the second type of adapter replaces the current shaft size to accommodate a large circular saw blade.

What blades are commonly associated with an arbor?

Most circular saw blades have a bore size to attach to the arbor of a circular saw. Except for the worm drive saw blades with a diamond arbor, not a regular arbor size, all of the blades use the arbors to securely attach to the circular saw.

Some of the popular options available are table saw blades, miter saw blades, panel saw blades, concrete saw blades, and abrasive saw blades.

Final Words

A circular saw is packed with many small tools and parts that play a significant role in executing a cut properly. However, the whole purpose of a circular saw would be defied if the blade is not attached properly and securely. So, an arbor undertakes such grave duty to hold the blade tightly. That is why it is the most important factor you must consider while buying a new blade.


My name is Michael M. Militello, and I want to help you find the right tools and the best products for your next project! As a professional tool expert here in Houston, TX, With my vast tool experience, I can help you choose the right brand, model, and size for the job. Please feel free to contact me with any questions you may have. You can reach me here on my blog and also on Facebook, Twitter , and Pinterest. I look forward to hearing from you!

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