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Allen Wrench vs Hex Key

A collage of hex key and allen wrench.

The Allen wrench and the hex key. Both are commonly used terms among everyone, from DIYers to professionals. And often, the terms are used interchangeably, which is not helpful when you’re trying to find the right tool to use.

This is a close look at a set of hex keys held together with a key ring.

So the question is, what exactly are hex keys and Allen wrenches? What are their differences and their purposes?

Well, we’ve got you covered. This guide is here to answer those questions for you.

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So, What’s the Difference Between an Allen Wrench and Hex Key?

The difference? There isn’t one. Allen wrenches, and hex keys are the same thing. “Allen” is simply a brand name.

Sometime in the early 1900s, William G. Allen of Allen Manufacturing patented the tool design. It was created to fit into screws with a hexagonal screw head and thus became known as a “hex key.”

So “Allen wrench” is the brand while “hex key” is the generic term. Though many companies now produce the product, many people still refer to them as Allen wrenches.

There are other names for them, too, including:

  • Hex wrench
  • Hex key wrench
  • Hexagon key

No matter what name you call them, they are all created for the same purpose.

And What is the Purpose of the Allen Wrench?

An Allen wrench is made to work with a hexagonal socket head. Let’s start with understanding why you would use a hex fastener over other screws.

This is a stainless steel allen bolt or screw with an allen wrench.

A hexagon socket has six pressure points, while regular screws come with only two or four. Therefore, your tool can grip the hex head better and turn easier. This leads to greater efficiency and less fatigue when putting items together.

A hex key adds to this efficiency. Not only does it fit the screw properly, but it also provides leverage. This makes it even easier to turn the screw.

This is a set of allen wrenches with a red holder.

As an added bonus, a hexagonal socket is harder to strip than other options. It’s not impossible to strip them. But, as long as you use the correct size hex key, you’re typically good to go.

Types of Hex Keys

On top of them having several names, hex keys come in many different types.


This is a close look at a single L-shaped black metal allen wrench.

Standard hex keys come in an “L” shape. This allows you to reach into tight spaces while also allowing you to exert enough force on the hex bolt.


A close look at a T-shaped allen wrench with easy to grip T-shaped handle.

A T-handle hexagon key is just how it sounds. The handle is in the shape of a “T” instead of an “L.” This form is popular when you need both leverage and speed for a hexagonal bolt head.

Folding Hex Key

This is a folding hex key with a rubberized grip.

You can purchase a hex key set that looks a bit like a Swiss Army knife. The keys fold up, so you can stick them in your pocket. These are handy for on-the-go use, like if you are out on a bike ride and need to tighten something.

While handy, it’s essential to understand that a folding hex key wrench set is not suitable for heavy-duty use. These keys are straight, not L-shaped. That means you cannot put as much force behind them.

P-Handle Allen Key

Park Tool PH-2 P-Handled Hex Wrench (2mm)

Click image for more info

Oddly enough, a P-handle hex key looks like a “P.” They are typically larger than other hex keys and provide a comfortable grip. You often see P-handle hex keys in several types of professional workshops.

Allen Screwdriver

This is a set of screwdrivers that has red grip support handles.

Again, the name says it all. You can purchase a screwdriver set that has hexagonal heads. They are often used when there isn’t enough space to turn an L-shape hex key.

Key Ring Sets

These are various sizes of black metal allen wrenches held together with a key ring.

Looking for a set to hang on the wall or even off a belt loop for when you’re working? You can get an Allen key ring set for that.

With these sets, each hex key is attached to the keyring by a spring. You can turn each hex key out of the spring to use it. To put it back, simply turn the hex wrench back into the spring.

Torque Wrench

This is a small torque wrench along with its bit tools.

Torque wrenches are a tool used to apply a specific amount of torque to your fastener, whatever type that might be. Fortunately, that means you can get hex bits to fit into hex screws.

Ball End Hex Keys

A single stainless steel allen key with a ball tip.

These are basically long arm hex wrenches that have a ball at the end. Ball end hex keys allow the flexibility you need to reach into tight spots.

Common Uses of Hex Keys

Hex keys are used for any item that has a hex screw. However, there are some areas that the use of hex keys is common, including the following.

Bicycle Repair

A person unscrews the handle of the bicycle with a hex key.

Hex screws are popular among bicycle manufacturers. Therefore, hex keys are literally the key to most bicycle repairs. If you are an avid bicyclist, be sure to keep some folding hex keys on hand.

Motorcycle and Car Repair

This is a mechanic repairing a motorcycle with an allen wrench.

You’ll likely notice some hex screws in your vehicle. Some of the most common places are in or around the glove compartment and under the seats. T-handle hex keys are usually best for these areas.


This is a close look at someone assembling the furniture with a hex key.

Hex screws are also popular among furniture makers. They are compact, meaning they are pretty easy to blend into the piece. To put together this furniture or tighten it up after use, you’ll need a set of hex keys.


An electronics gadget with its cover being unscrewed with a hex key.

The smaller electronics get, the smaller their components become. When beneficial, electronics manufacturers use hex screws due to their compact size.

Tool and Machinery Repair

This piece of machinery is being repaired using a hex key.

Another bit of irony. You actually need tools to repair tools. Several heavy-duty tools and machinery require some adjustments via a hex key.

Frequently Asked Questions

What is the difference between the long arm and short arm hex keys?

The difference is that a long-arm hex key comes with a longer handle. Typically, it’s about 50% longer than a short arm hex key.

What should I look for in a hex key wrench set?

This really depends on what you need it for, especially when it comes to size. If you just want to keep an Allen wrench set around for basic use, like furniture around the house, a standard set should be good enough.

However, if you own a workshop, mechanic shop or need them for some other profession, you might want to buy a set with additional sizes.

Additionally, you’ll have to decide which type of hex key is best, such as L-shape or T-handle. As mentioned above, different uses often require or benefit from a different type. Many people, especially those that use them a lot, benefit from having multiple types in the toolbox.

What sizes does a standard set come with?

First, it’s important to know that you can get sets in both SAE and metric sizes. The most common metric wrenches come in sizes ranging from 1.5 mm to 10 mm. The most common SAE sets typically come with a minimum of 1/8 inch, 3/32 inch, 7/64 inch, 5/32 inch, 3/16 inch, ¼ inch, and 7/32 inch.

Some sets come in fewer or more sizes, so it’s important to shop around for what you need.

Where are the best places to buy an Allen key set?

Again, this depends on your needs. You can find an affordable standard set just about anywhere — Walmart, Lowe’s, Home Depot, and sometimes even dollar stores. If they are for personal, around-the-house use, any of these places are good options.

If, on the other hand, you need them for work or need non-standard sizes, you might need to shop elsewhere. Lowe’s and Home Depot might have what you need. However, looking at places like Bondhus, car parts suppliers, and similar specialty stores might offer more of what you need.