Monkey Wrench vs. Pipe Wrench: What's The Difference Between Them?

There are many types of wrenches on the market, from pipe wrenches, to torque wrenches, to ratchet wrenches, to monkey wrenches. Today we’re going to look at the two that get confused the most: monkey wrenches and pipe wrenches.

The difference between a monkey wrench and a pipe wrench is not the easiest question to answer. National and regional differences change the way tools are referred to. For example, a wrench in the United States is a spanner in the United Kingdom.

In some places, what most people call a “pipe wrench” is called a “monkey wrench”, and in others, both different tools are called the same thing. To be able to discern the difference between these two tools, we need to define our terms, and set a clear definition for each one and what it does.

To do that, we’re going to have to make a choice about which tool is the “monkey wrench”, and which is the “pipe wrench”. To be the most inclusive, and to ensure that we end up being correct most of the time, in most of the world, we’re going to stick with the most commonly accepted and widely distributed definitions.

What Is A Monkey Wrench?

The monkey wrench was one of the first adjustable wrenches, and as such it revolutionized many industries that previously relied on bulky sets of fixed wrenches in various sizes. This time-saving and space-saving tool was essential during the second industrial revolution and beyond, but nobody really knows when and where the original monkey wrench was invented, though it's estimated to be around the mid-1800s.

There are numerous competing claims to its origin, such as that it was invented by an American mechanic named Charles Moncky (who may not have ever existed). The most credible idea, however, is that various different people had invented adjustable wrenches all around the same time, in different countries around the world, and they were then popularized by brands like BAHCO in the late 1800s and early 1900s.

While the term “monkey wrench” can technically be applied to any adjustable wrench (including pipe wrenches), in most of the world it most accurately describes an adjustable spanner, which is a wrench that has a jaw that opens and closes horizontally, like you can see here. The jaws of the wrench are in-line with the handle, and they open outward from the tip of the tool.

Monkey wrenches typically have smooth, flat jaws that are completely parallel to each other, as can be seen on this stubby lightweight monkey wrench from Tone. And while not always the case, are most-often made of steel with a silver or chrome finish like this wrench from Engineer, and are very rarely colored.

Monkey wrenches are a favorite tool among automotive mechanics, machinery maintenance workers, and general handymen as they're designed to easily tighten and loosen hexagonal nuts and bolts without damaging them, thanks to their smooth jaws.

What Is A Pipe Wrench?

The origin of the adjustable pipe wrench, unlike the monkey wrench, is clearly documented. It was invented by an American machinist named Daniel Stillson in 1869, and quickly became an indispensable tool in the plumbing and construction industries. 

Pipe wrenches have jaws that open and close vertically, the tip of the tool extends, and the mouth opens on the side of the handle. This is one of the major differences in design between monkey wrenches and pipe wrenches. As with a monkey wrench you approach the target directly from the tip of the tool, while with a pipe wrench you approach it from the side of the tool. However, there are also offset pipe wrenches that have twisted heads, allowing you to approach pipes head-on, like if you were using a monkey wrench.

The other key difference in design is that pipe wrenches have serrated jaws, and the top jaw is typically tilted, so that they're not perfectly parallel, as seen on this pipe wrench from Tone. The serration and the tilting allows the jaws to grip and apply pressure to rounded objects. While monkey wrenches are designed for rotating hexagonal objects like nuts and bolts, pipe wrenches are designed for rotating round objects, like pipes and pipe fittings. 

One final thing that sets pipe wrenches apart from monkey wrenches is that, although they’re sometimes silver, like these aluminum pipe wrenches, they’re most commonly red and black, like these wrenches from MCC.

Pipe wrenches are typically used by plumbers and gas fitters for work with water and gas pipes, but are also used by HVAC workers and less commonly in some other trades involving pipes. 

What’s The Difference Between A Monkey Wrench And A Pipe Wrench?

Because there are no globally-accepted definitions of what is a pipe wrench, what is a monkey wrench, and how they differ, we can only really talk in general terms. Regional differences have made the task of separating these tools complex, as in some places, monkey wrenches are pipe wrenches, or both the wrenches we’ve described are called one or the other. 

However, as it’s generally understood in most of the world and, as trends tend to follow the majority, will eventually become the globally-accepted definition, the differences are as follows:

• Monkey wrenches are designed for flat-sided fasteners, pipe wrenches are designed for round pipes and round fasteners.
• Monkey wrenches have flat, parallel jaws, pipe wrenches have serrated, skewed jaws.
• Monkey wrenches have jaws that open horizontally, pipe wrenches have jaws that open vertically.
• The jaws of a monkey wrench open on the tip of the tool, the jaws of a pipe wrench open on the side of the tool.
• Though not always the case, monkey wrenches are silver/chrome, and pipe wrenches are red and black.
• Monkey wrenches are typically used by auto mechanics and machinery workers, pipe wrenches are typically used by plumbers and gas fitters.

If you follow these two imperfect definitions of monkey wrenches and pipe wrenches, and treat the word “monkey wrench” to refer to the tool that works with bolts and “pipe wrench” to refer to the tool that works with pipes, you will be correct in most of the world. 

Although you may end up mistaken in some regions, the erasure of regional differences in language thanks to the dissemination of knowledge we enjoy in the modern world means that you'll probably be correct everywhere soon enough.

If you’ve been puzzled about the differences between monkey wrenches and pipe wrenches, I hope we’ve been able to answer some of your questions. While the answer may never be crystal clear, the standard is that monkey wrenches work on nuts and bolts, and pipe wrenches work on pipes and pipe fittings.

Do you use monkey wrenches or pipe wrenches a lot in your job? What do you find them most useful for? Let us know in the comments.