What are SAE Wrenches & Sockets?

by MOTORHEAD Tools Team on May 18, 2021

What are SAE Wrenches & Sockets?

If you’re a first-time homeowner, a car or mechanic enthusiast, or a DIY-er looking to start working on various projects, you probably ended up here trying to decipher what an SAE wrench and socket is. This article will arm you with the knowledge on what the difference is between SAE and metric wrenches and sockets, drive sizes of each, along with common SAE socket sizes. You’ll also have a handy resource to know whether or not SAE and metric are interchangeable, and how you’ll know what size to get depending on what you’re working with. Let’s get started. 

What does SAE measurement stand for?

First things first, what does SAE exactly stand for? SAE stands for Society of Automotive Engineers. This form of measurement was used primarily on cars made in the USA. This is why more often than not if you’re in the United States, you’re most likely finding wrenches and sockets in SAE sizings. AE sockets are sized in inches and fractions of inches.

SAE & Metric: What’s the Difference?

SAE sockets are sized in inches and fractions of inches. Metric and SAE wrenches have different systems of measurement. Metric sockets and wrenches use the metric measurement system. This is when millimeters are used to describe the size. So you’d get a 20mm wrench in the metric unit of measurement. SAE wrenches use the imperial measurement system, mostly used in the United States, where it’s described using inches, or fractions of an inch. For this, you’d get a 1/3inch wrench or socket. 

Typically, SAE sockets and wrenches are used on American-made cars, as mentioned previously, however, when it comes to working on imported cars (assuming you’re in the USA) you’ll most likely be looking for metric units of measurement. Keep reading to find out if you can use either or. 

Both the SAE and metric fasteners have six-sided heads that are turned using open-end, boxed or socket wrenches. Socket wrenches have the constant contact with all sides of the bolt head and also have a ratchet system for easier and faster operation in either direction.

Drive sizes of SAE and Metric Wrenches

Typically, SAE and metric come in three drive sizes: 

  1.  ¼
  2.  ⅜
  3.  ½

Metric sockets use imperial-sized drivers and the drive dimensions follow in US sizes, such as 1/4″, 3/8″, 1/2″, ¾. This means you can use the sockets whether it’s metric or SAE. 

Logically, smaller sockets would use smaller drive sizes, and larger sockets use larger drive sizes. For example, a 6mm socket in metric, will most commonly be sold in the 1/4″ SAE drive size.

Common SAE socket sizes

The most commonly used and sold SAE sizes for wrenches and sockets are: 

  • 5/16″
  •  3/8″
  • 7/16″
  • 1/2″
  • 9/16″
  • 5/8″
  • 11/16″
  • 3/4″
  • 13/16″
  • 7/8″
  • 1″
  • 1-1/4″
  • 1-7/16″
  • 1-1/2″ 

Of course, you get larger sizes, however, those aren’t very typical, or are only needed for specialized cases. 

Are SAE & Metric Interchangeable?

Can you use Metric sockets on SAE fasteners or SAE Sockets on Metric Fasteners? Yes, you can use some sockets on both metric and SAE sizes. However, you need to be careful, as most times they are not exactly the same, and you can strip a bolt by using an SAE socket on a metric bolt and vice versa.

Should I buy metric or SAE wrenches? 

Depending on the type of work you’ll be doing, or parts you’re working with, you’ll likely get away with using either. For your convenience, we;ve compiled the below SAE to Metric and Bolt conversion chart!

SAE Wrench Size

Bolt Size (SI)

Metric Wrench Size



8 mm



10 mm



11 mm



13 mm



14 mm



16 mm



19 mm



21 mm



22 mm



24 mm

If you found this article helpful, be sure to stick around for more tool tips and tricks.


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