Buying an Adjustable Wrench: What Size Do You Need?

Every person working on a DIY project has encountered this problem: you have the right sized nut, the right bolt and somehow, you cannot find a wrench that fits perfectly. It’s too loose or too small and only sometimes do you get that Goldilocks “just right.” However, an adjustable wrench can fix that problem.

How do I know what size wrench I need? To determine the size of the wrench that you need, first assess the demands of the job for which it will be needed. There are 3-4 different types of adjustable wrenches that can handle most jobs, so knowing how your job fits into the capability of each wrench will be the key factor in making your choice. 

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For the average person, it’s not viable to have a huge toolbox with a range of tools for every job, and that’s where the adjustable wrench comes in. One size fits all…or almost all.

What is an Adjustable Wrench?

For the novice DIY handyperson, an adjustable wrench is a tool used to tighten or loosen components that are screwed together. These are generally items like nuts and bolts, or pipe fittings (source).

Sometimes, an adjustable wrench can also be called a spanner. The wrench is used for many tasks around the house and should be a vital item in every toolbox. 

An adjustable wrench is generally bigger than your non-adjustable counterpart, but the size allows it to work for a range of tasks. An adjustable wrench will also have a locked and moveable jaw that allows you to adjust to the task at hand.

Wrench and Nut Sizes

When it comes to wrenches, it’s important to understand what is meant by the wrench/spanner size. The size of a wrench refers to the distance across the nut that it would fit if it is measured in millimeters. 

If the size is presented in inches, it refers to the length of the handle. A longer handle indicates that the jaw can be opened further. An adjustable wrench would obviously be able to fit a variety of sizes.

When wrenches are used to loosen nuts, they are generally used for hex (hexagonal) nuts. Hex nuts and bolts are used in construction and machinery, and therefore are secure and difficult to remove (source). Sizes with nuts and bolts are standardized and a bolt labeled ⅜” will fit a nut labeled ⅜”. 

Types of Adjustable Wrenches

Usually, one type of adjustable wrench should be enough for your needs, but there is a range to choose from which may assist you in making a decision. 

Adjustable Spanner/Wrench

Also known as a crescent wrench, this is the most common type of adjustable wrench. A good wrench should have a wide jaw capacity but also be a manageable length for storage purposes. The handle should be wide and preferably rubberized for more comfort and easier control. 

Adjustable wrenches use either a worm gear, a little barrel which is turned to adjust the wrench. Newer models now come with a sliding gear that uses a slider to adjust the size of the wrench’s opening.

What is a adjustable spanner/wrench it used for?

The adjustable wrench has a variety of purposes, from plumbing (loosening and tightening pipes and faucets) all the way to opening a stubborn lid on a jar (source). It can also be used for vehicle repairs and most motorcyclists swear that it is a tool that should always be kept on hand.

How do you use a adjustable spanner/wrench

Once the nut that has to be tightened or loosened has been identified, open the adjustable wrench jaws by turning the screw mechanism. It should be opened a little wider than the size of the nut.

Place the jaws over the nut and while holding it in place, tighten the jaw using the screw mechanism so it clamps tightly around the nut. An old idiom, “righty tighty and lefty loosey” is an easy way to remember which way to turn the nut. Loosen the wrench once the job is complete.

What sizes are available for a adjustable spanner/wrench

These wrenches come in sizes ranging from 4-24 inches, and this refers to the length of the handle. A good wrench should be made of high-quality chrome-vanadium steel that will last for years. The size required here will depend on storage space, but it is possible to find wide crescent wrenches with short handles.

Monkey Wrench

The monkey wrench, surprisingly enough, has no connection to monkeys or simians of any kind. In the 19th century, the term ‘monkey’ was used to sailors to describe small tools that were made for specific work, and that is where the tool gets its humorous name (source).

Some people use the phrase ‘monkey wrench’ interchangeably with a crescent wrench, but a monkey wrench is quite unique. It shares more similarities with a pipe wrench but differs with its sharp jaws and long handles.

The shape of the wrench is similar to the letter ‘F’ and instead of adjusting horizontally as the crescent wrench does, it adjusts vertically, closing its jaws like a mouth. Its jaws are generally slightly serrated and a worm gear is used to close the jaws from the bottom.

What is a monkey wrench used for?

A monkey wrench is most useful for tasks that require reach, especially those in plumbing and mechanical repairs. Its long handle allows the user to delve deep into the bowels of a machine and extends itself into hard to reach areas.

It’s preferable to use the monkey wrench for hex nuts as the jaws allow for an excellent grip.  However, it is not suggested for plumbing newer pipes made of softer metals as the straight jaws could damage them.

For DIY jobs around the home and garage, the monkey wrench is a better buy as it allows users to work with hex nuts that can be difficult to loosen or tighten without the correct spanner size. 

How do you use a monkey wrench?

In a manner similar to the crescent wrench, a monkey wrench should be opened up to a size slightly larger than the nut. It should be tightened around the nut and then slowly turned to loosen or tighten the nut.

What sizes are available for a monkey wrench?

Monkey wrenches come in a range of sizes, usually starting at 8 inches continuing up to 48 inches for industrial size nuts. It is unlikely that the average home user will need something that extreme so most monkey wrenches stick within the 8-18 inch range (source).

Pipe Wrench

At first glance, it is difficult to see any difference between a monkey wrench and a pipe wrench. They both have large heads, thick handles, and serrated jaws. Their construction looks quite similar as well.

However, the easiest way to see the difference between them is in the curve of the jaw. A monkey wrench’s jaws are always straight and show no gaps when closed completely against the upper jaw, but a pipe wrench’s jaws are slightly curved. Perfect for holding on to a pipe.

What is a pipe wrench used for?

The name is a giveaway but pipe wrenches are used for turning, loosening and tightening pipes. The jaws are made to be less harsh on soft materials so a pipe wrench can be used safely on a range of pipes, from plastic to copper.

A pipe wrench is most often used for plumbing jobs and if that is what is primarily needed around the house, get a pipe wrench. 

How do you use a pipe wrench?

It is preferable that pipe wrenches only be used on pipes. Due to its shape, it is prone to breakage if used on a square or hexagonal shape. 

When using a pipe wrench, make sure that there is a little space between the pipe and the back of the hook jaw (upper jaw). This allows for proper gripping motion and reduces the chance of the wrench slipping (source).

What sizes are available for a pipe wrench?

There are several different sizes available, similar to monkey wrenches. For the most part, an 8-inch to 12-inch pipe wrench should be adequate for any home user.  Below are a few suggested pipe size ranges that you can work with (source).

Suggested Pipe Size Range 

Pipe Wrench SizeSuggested Pipe Size Range
6”⅛” – ½” 
8”¼” – ¾” 
10”¼” – 1”
12”½” – 1 ¼”  
14”½” – 1 ½” 
18”1” – 2”
24”1 ½” – 2 ½” 
36”2” – 3 ½”
48”3” – 5”

Basin Wrench

Also known as a plumber wrench or sink wrench, this is a lesser-known wrench with a very unique look. 

The head of the wrench is C-shaped with a flat base, and the handle is generally extendable. The jaws are serrated and the head is generally able to swivel to allow for movement in spaces that are restricted.

The end has a thin steel bar threaded through for easy turning, even with one hand. The jaws are spring-loaded, which allows for automatic latching to the nut. Higher-end models can even have lamps for easy viewing in dark areas (source).

What is a basin wrench used for?

The name is a giveaway. This wrench is used to get to hard-to-reach hex nuts under a basin. While this type of wrench is used primarily by plumbers, the amount of dexterity and convenience it provides can be useful for any DIY work that involves fiddly nuts.

How do you use a basin wrench?

The wrench is particularly easy to use as it does not require any tightening. To begin with, the head of the wrench should be facing the right way to be able to surround the nut horizontally. For most basic wrenches, the head can be manually swiveled to allow for this. 

Using one hand to hold the wrench steady and the other on the handle, the head of the wrench should be moved to surround the nut. The flat side should be on one of the flat angles of the nut while the C-shaped head should surround the rest of the nut.

The spring-load head should grip the nut and by turning counter-clockwise, the nut attached to the basin should come loose. By turning the handle of the basin wrench clockwise, the nut will be released to allow the wrench to return to the original position, gripping the nut again to continue loosening.

What sizes are available for a basin wrench?

There are a wide variety of sizes available for basin wrenches, but most of them are able to fit nuts of various sizes. They typically come in sizes that can be used on nuts ranging from ⅝” to 2-inches. 

Some models of basin wrenches allow for interchangeable jaws that can be bought as a set or separately to allow for a range of sizes. 

Chain/Strap Wrench

This is a wrench that most people haven’t heard of. The chain wrench is a wrench that uses an adjustable chain to wrap around objects like pipes to secure it (source). It is a good alternative to a pipe wrench and can be handy for plumbing projects.

A chain wrench is made up of a long, thin handle that attaches to a wider head. The head has a chain attached to one side and there are little supporting hooks on the other side of the head that allow the chain to be pulled taut and held in place.

A strap wrench has the same functionality except it uses a wide piece of plastic instead of a chain. This allows for usage on more delicate items that might be damaged by using the chain wrench, which has a tendency to destroy finishings, especially on wooden objects.

What is a chain/strap wrench used for?

It is primarily used in plumbing and building projects as the wrench can be used to turn large pipes. Its adjustable chain engages the pipe and allows for easy movement. It can also be used to hold pulleys and other awkwardly shaped objects that need to be held steady.

How do you use a chain/strap wrench?

The chain wrench is very simple to use. However, to use it, there has to be some space around the pipe or object that is being turned. Space is needed to thread the chain through. 

Once the chain has passed around the object, the teeth on the chain can be hooked into the spaces provided. The chain should be tight and rigid to achieve the best results and the upper part of the head should be flush against the object. 

The pipe can then be held in place or moved around as necessary. To unhook the chain, the head of the chain wrench should be shifted upward, which releases a little space and the chain can easily be removed. 

What sizes are available for a chain/strap wrench?

A chain wrench has a lot of flexibility and one size should be adequate for most DIY projects. When buying a wrench, ensure the specifications of handle and chain length. A 20 to 24-inch chain wrench should be more than adequate for any household project (source).

Advantages and Disadvantages of Wrenches


Adjustable wrenches are an affordable method of providing any DIY enthusiast a lot of flexibility when it comes to projects. Having a few types of adjustable wrenches means that any project is possible.


Some wrenches are prone to damaging objects and pipes. A monkey wrench is too harsh for soft metals and woods, which makes a pipe wrench more appropriate when dealing with more malleable metals. 

However, if the pipe or object is exposed and no damage should be risked, then a strap wrench would be the most appropriate wrench to use in that scenario. 

It is also important to ensure safety procedures when using adjustable wrenches, as they are more prone to slipping. Serrated teeth on wrenches should be cleaned often to make sure that they continue to grip properly.

Importance of Wrench Size

There are several methods of calculation used to measure sizes used in wrenches and nuts. In the United States, the Society of Automotive Engineers (SAE) standard is used. It uses inches as a unit of measurement.

The inches presented refers to the flat of the head of a bolt. Since adjustable wrenches can be made wider as needed, it is only important to have different types of adjustable wrenches to complete projects instead of having a large set of fixed-size wrenches.

When using a wrench, ensure that the correct wrench is chosen for the job. When tightening adjustable wrenches, wiggle the wrench slightly once tightened to ensure a strong hold. 

If there is a lot of wiggle, readjust the wrench as adjustable wrenches can round off corners of bolts and nuts if adjusted poorly. 

Final Thoughts

There are many advantages of adjustable wrenches, from their affordability to their convenience. However, it is just as important to ensure that the wrench is used correctly for the job that it is made for.

Buying an adjustable spanner is a smart choice for anyone. A builder is only as good as his weakest tool and a hardy adjustable wrench will serve them for many years to come.

Related Questions

What are the different sizes of wrenches? The different sizes of wrenches include 1/4, 5/16, 11/32, 3/8, 7/16, 1/2, 9/16, 5/8, 11/16, 3/4, 13/16, 7/8, 15/16, 1.

Is 24mm and 15/16″ the same? 24mm and 15/16″ are the same.

Is a crescent wrench the same as an adjustable wrench? A crescent wrench and adjustable wrench are slightly different. An adjustable wrench has one fixed jaw and one adjustable jaw which allows you to use it on a wide variety of fastener sizes. A crescent wrench is usually angled at 22 1/2 degrees to the handle so that the wrench can be flipped over to provide two different gripping positions in tight spaces

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