What Size Allen Wrench for Brake Calipers?

Do you know what size Allen wrench for brake calipers? Here are some of the steps that can help to guide you in the right direction.

To prevent vehicle failure, you need to keep the engine in check, change the oil, examine the brakes, and so on.

A routine car inspection becomes more comfortable if you have the right set of tools. By the right set of tools, we mean versatile instruments that can be used for multiple purposes. Such a tool is an Allen wrench, which is functional and available in a wide range of sizes. This tool can save you from the cost of regular visits to your mechanic.

But many ask, what size Allen wrench for brake calipers?

Selecting the right size of this handy tool can often be confusing.So, here’s a step-by-step breakdown of exactly what you need to do to determine the appropriate size of Allen wrench for brake calipers.

Related Reads: Top Rated Tool Backpack for Mechanic

The Available Size Range Of Allen Wrench

Allen wrench is composed of premium-quality steel. These are L-shaped tools with uneven arms. Each of these is made to fit screws with specific socket sizes, so the tools are typically sold in a bunch with variable sizes. Allen Wrench is famous for its versatility. These tools are made in metric sizes as well as standard sizes.

What Size Allen Wrench for Brake Calipers

European Standard Sizes

In Europe, metric sizes are taken as standard. Some of the distinctive sizes are:

• 1.5mm
• 2mm
• 2.5mm
• 3mm
• 4mm
• 5mm
• 5.5mm
• 6 mm
• 7 mm
• 8 mm
• 9 mm
• 10 mm

Among these, 2.5 mm, 3 mm, 4 mm, 5 mm, 6 mm, 8mm, and 10 mm are more prevalent than the others.

Standard Sizes

The inch-based set of Allen wrenches are often considered to be standard within the industry. Some of these sizes are:
• 1/8 inch
• 3/32 inch
• 7/64 inch
• 5/32 inch
• 3/16 inch
• ¼ inch
• 7/32 inch

Determining Allen Wrench Size to Use for Brake Calipers

Identifying the right size of Allen wrench can especially be difficult for an amateur. So, to make things easier, here are some of the steps that can help to guide you in the right direction.

Steps Determining Allen Wrench Size

Step 1: Measuring the diameter of the screw

Usually, the appropriate size of the hex key is ascertained by measuring the diameter of the screw. But guessing the right size can be slightly challenging for a beginner.

To avoid this confusion, the simplest thing that you can do is select a medium-sized wrench from the set and see if that fits. If it doesn’t, then just work your way up or down the sizes accordingly.

Step 2: Select a suitable size

For brake calipers, the most appropriate measure, to begin with, would be 7 mm. Some people prefer using a 6 mm wrench key, while others prefer a 9 mm one. But a 7 mm Allen wrench has been favored by most individuals.

This particular size is usually sold separately.The 7 mm hex keys are frequently used for the front brake in many cars.They help to reach even the tight and supposedly unreachable spots and provide leverage according to necessity.

Step 3: Clean the Allen wrench before beginning work

Before placing an Allen wrench into a hex bolt, make sure you properly clean the head to make sure there aren’t any reduce dirt or lumber on it.

You can use a Q-tip soaked in rubbing alcohol to get rid of the dust accumulated on the corners of the hexagon.

Step 4: Check if the hex key is adequately aligned with the bolt or not

Prior to tightening or loosening a bolt, ensure that each side of the Allen wrench is firmly and accurately aligned. If proper attention is not paid at this point, you might strip the bolt head or end up damaging the wrench.

Step 5: Look for alternative options

Ratchet Allen Keys are similarly handy and commonly preferred by professionals when working with rotor bolts. These come in numerous different sizes. So, choose one that correctly fits the bolts.

These tools are readily available in any hardware store as well as in the tools section of auto parts chain stores. Every avid car enthusiast should have these tools in their toolbox.

What Should You Consider While Purchasing Allen Wrench

Shopping for an Allen wrench can be overwhelming and confusing especially, for beginners. So, here are a few tips that you can keep in mind when you visit your local hardware stores.

Buying Guide for Allen Wrench

• Evaluate the Quality of the Tools

Visiting local hardware stores will provide you with numerous options at variable price ranges. Although it might seem reasonable to you to purchase cheaper options, that is an entirely wrong move. When it comes to tools, you want to invest in high-quality ones.

• Try Not to Settle for Low-Priced Tools

Cheaper working tools lack not only durability but also tolerance. Inexpensive hex keys often end up stripping the bolts, which can never be good. Instead, it increases the problems that already needed a fix.

• Be Wary of China-Made Products

It is always wise to invest in tools made in the USA or Europe as they tend to be of superior quality. However, these are a bit expensive than the Chinese options but totally worth the extra penny.


Only one specific sort of Allen wrench is not sufficient to carry out a smooth maintenance job; different styles of hex keys are needed to be used for different parts.

You can get your job done with almost any hex key, but to do it proficiently and potentially get better results, you should find the accurate size of Allen wrench that fits the screw or bolt.

And since you’ve read our article, you should now know the answer to the question, what size Allen wrench for brake calipers.

Let us know if you have any more questions.


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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