Garage Tools 101: Hex Key vs. Allen Wrench

There are a lot of garage tools out there, many of which are essential for various DIY projects. Hex keys and Allen wrenches are staples of many tool boxes around the country. But you might be wondering, “What’s the difference between an Allen wrench and a hex key anyway?” Let’s find out.

Hex Key vs. Allen Wrench Differences

The only difference between an Allen wrench and a hex key is their names. It’s no use comparing what’s better when comparing an Allen wrench vs. a hex key because they’re essentially the same tool. Both names are used to describe a six-sided, L-shaped tool used to tighten or loosen fasteners that have six-sided openings. These tools come in various sizes but are generally compact and easy to maneuver in tight spaces.

The name “hex key” is the broader term, and it comes from the tool’s shape. The Greek word “hex” means six, and it perfectly describes the tool’s hexagonal, six-sided shape. As for the “key” portion of the name, that comes from how the tool fits into the six-sided fasteners. It slides into the shape much like how a key slides into a lock, hence the name.

The term “Allen wrench,” on the other hand, comes from the 1900s inventor, William G. Allen, who was responsible for patenting the original tool’s design, as well as the iconic six-sided fasteners. These fasteners have only gotten more popular since Allen’s time.

Hex keys go by many other variants of these two names, like hex wrench and Allen key. “Allen key” is a trademarked name that’s since become so tied to the tool that other manufacturers use the Allen name to describe their products as well.

Hex Key Uses

Thanks to their small size and easy maneuverability, there are many uses for hex keys and their related fasteners. Hex key fasteners are popular in the automotive industry, plumbing, and construction. If you buy a hex key set for your garage toolbox, you’ll likely be able to pull it out for other things as well.

For automotive repair, you’ll usually use a set of hex keys to replace brake pads, change oil filters, and adjust your vehicle’s brakes. There are various fasteners around the brake calipers and gas tank that use hex key fasteners as well.

How To Use a Hex Key

Using a hex key is fairly simple, but we’ve compiled some helpful tips.

Step One: Inspect the Fastener

Before you slot in the hex key, double-check the associated fastener. Check that it isn’t stripped and that you’re using the right hex tool size for it. If the fastener has a tamper-resistant pin, you’ll need to use a tamper-resistant hex key to remove it.

Step Two: Wear the Correct Gear

Hex keys typically don’t have a handle, and they’re designed to fit in small, tight spaces to remove the related fasteners. This means that you might hurt your hands if you aren’t careful when using them. Wear a set of gloves to protect your hands when using hex keys.

Step Three: Position the Hex Key Properly

It’s always best to position the hex key perpendicular to the fastener when inserting it. The hex key’s L-shaped design is designed to form a right angle when one end slots into the hex key fastener. 

Step Four: Turn the Hex Key

Turn the hex key clockwise to tighten the fastener and counterclockwise to loosen it. Be careful not to overtighten the fastener, or you might risk stripping the fastener or damaging your hex key. If the fastener is stuck, you can try applying penetrating oil or heating it using a hairdryer.

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Hex Key Types

While the standard hex key is the L-shaped tool we described earlier, there are various hex key types and sizes available on the market. You’ll often find hex keys sold as a set of 7 to 12 differently sized pieces. The most common hex key size you’ll need for automotive fasteners is the 5/32-inch hex key.

Here are some of the other hex key types out there:

Ball-Ended Hex Keys

Some hex keys have a ball-shaped end that makes it easier to access angled fasteners. The balled end makes insertion much easier, and it allows you to turn the hex key even when it’s at an angle. This is usually best for low-resistance fasteners. Trying this technique on fasteners with higher resistance might strip the fastener.

Hex Screwdrivers

Hex screwdrivers have a proper handle and are straight rather than L-shaped. It’s easier to grip but more difficult to maneuver in tight spaces under the hood.

Hex Bits

Hex bits fit in drills, socket and ratchet sets, and impact drivers. This makes turning them that much simpler, but too much force can strip hex key fasteners. 

Alternative

If you don’t have any sort of hex key on hand and you urgently need to get a hex key fastener off, you can try using an adjustable wrench.

Now that you know a hex key is simply an Allen wrench under a different name, you can properly stock your garage toolbox with them. They’re very handy to get to those hard-to-reach areas, and you’ll never know when you might need one.