I used to have all of the SAE standard wrench and socket sizes in order memorized and could tell you instantly what size was next in order from small to large and which metric socket or wrench was equivalent. That was decades ago, back in my days as a mechanic and industrial technician.
In the years since, I've completely forgotten where some of the most common box end, open end wrench and socket sizes fit in. After a quick search yielding no real good results containing all of this information, I've decided to create a reference SAE (inches) + Metric (mm) page and size chart for myself and others to refer to. So without further ado, here are the results.
Standard Wrench Sizes Chart | Socket Sizes in Order
Standard Wrench and Socket Sizes Chart with Metric Conversions: The following chart lists the most common standard wrench and socket sizes, including their corresponding sizes one step smaller and larger, as well as the metric equivalents. For easy reference, you can also download the SAE Size and Metric Equivalent Conversion Table as a PDF file.
| SAE Size | One Size Smaller Than | One Size Bigger Than | Metric Equivalent |
|---|---|---|---|
| 1/4" | 5/16" | --- | 7 mm |
| 5/16" | 3/8" | 1/4" | 8 mm |
| 3/8" | 7/16" | 5/16" | 10 mm |
| 7/16" | 1/2" | 3/8" | 11 or 12 mm |
| 1/2" | 9/16" | 7/16" | 13 mm |
| 9/16" | 5/8" | 1/2" | 15 mm |
| 5/8" | 11/16" | 9/16" | 16 mm |
| 11/16" | 3/4" | 5/8" | 18 mm |
| 3/4" | 13/16" | 11/16" | 20 mm |
| 13/16" | 7/8" | 3/4" | 21 mm |
| 7/8" | 15/16" | 13/16" | 23 mm |
| 15/16" | 1" | 7/8" | 24 mm |
| 1" | 1-1/16" | 15/16" | 26 mm |
| 1-1/16" | 1-1/8" | 1" | 27 mm |
| 1-1/8" | 1-1/4" | 1-1/16" | 29 mm |
| 1-1/4" | 1-5/16" | 1-1/8" | 32 mm |
| 1-5/16" | 1-3/8" | 1-1/4" | 34 mm |
| 1-3/8" | 1-7/16" | 1-5/16" | 35 mm |
| 1-7/16" | 1-1/2" | 1-3/8" | 37 mm |
| 1-1/2" | 1-9/16" | 1-7/16" | 39 mm |
| 1-9/16" | 1-5/8" | 1-1/2" | 40 mm |
| 1-5/8" | 1-11/16" | 1-9/16" | 42 mm |
| 1-11/16" | 1-3/4" | 1-5/8" | 43 mm |
| 1-3/4" | 1-13/16" | 1-11/16" | 45 mm |
| 1-13/16" | 1-7/8" | 1-3/4" | 47 mm |
| 1-7/8" | 1-15/16" | 1-13/16" | 48 mm |
| 1-15/16" | 2" | 1-7/8" | 50 mm |
| 2" | --- | 1-15/16" | 51 mm |
Standard Wrench Sizes In Order | Smaller or Larger | SAE to Metric equivalent
Below is a list of commonly used SAE (Imperial) Standard and Metric wrench and socket sizes in ascending order up to 2 inches. For each size, I also mention one size smaller (step down) and the next size bigger or larger (step up), along with their equivalent size in Metric or mm.
Standard Wrench Sizes in Order | (Smaller than) | (Larger than) | (Equal to in mm):
- 1/4" (1/4" is one size smaller than 5/16") (5/16" is one size bigger than 1/4") (Equal to 7 mm in Metric)
- 5/16" (5/16" is one size smaller than 3/8") (3/8" is one size bigger than 5/16") (Equal to 8 mm in Metric)
- 3/8" (3/8" is one size smaller than 7/16") (7/16" is one size bigger than 3/8") (Equal to 10 mm in Metric)
- 7/16" (7/16" is one size smaller than 1/2") (1/2" is one size bigger than 7/16") (Equal to 11 or 12 mm in Metric)
- 1/2" (1/2" is one size smaller than 9/16") (9/16" is one size bigger than 1/2") (Equal to 13 mm in Metric)
- 9/16" (9/16" is one size smaller than 5/8") (5/8" is one size bigger than 9/16") (Equal to 15 mm in Metric)
- 5/8" (5/8" is one size smaller than 11/16") (11/16" is one size bigger than 5/8") (Equal to 16 mm in Metric)
- 11/16" (11/16" is one size smaller than 3/4") (3/4" is one size bigger than 11/16") (Equal to 18 mm in Metric)
- 3/4" (3/4" is one size smaller than 13/16") (13/16" is one size bigger than 3/4") (Equal to 20 mm in Metric)
- 13/16" (13/16" is one size smaller than 7/8") (7/8" is one size bigger than 13/16") (Equal to 21 mm in Metric)
- 7/8" (7/8" is one size smaller than 15/16") (15/16" is one size bigger than 7/8") (Equal to 23 mm in Metric)
- 15/16" (15/16" is one size smaller than 1") (1" is one size bigger than 15/16") (Equal to 24 mm in Metric)
- 1" (1" is one size smaller than 1-1/16") (1-1/16" is one size bigger than 1") (Equal to 26 mm in Metric)
- 1-1/16" (1-1/16" is one size smaller than 1-1/8") (1-1/8" is one size bigger than 1-1/16") (Equal to 27 mm in Metric)
- 1-1/8" (1-1/8" is one size smaller than 1-1/4") (1-1/4" is one size bigger than 1-1/8") (Equal to 29 mm in Metric)
- 1-1/4" (1-1/4" is one size smaller than 1-5/16") (1-5/16" is one size bigger than 1-1/4") (Equal to 32 mm in Metric)
- 1-5/16" (1-5/16" is one size smaller than 1-3/8") (1-3/8" is one size bigger than 1-5/16") (Equal to 34 mm in Metric)
- 1-3/8" (1-3/8" is one size smaller than 1-7/16") (1-7/16" is one size bigger than 1-3/8") (Equal to 35 mm in Metric)
- 1-7/16" (1-7/16" is one size smaller than 1-1/2") (1-1/2" is one size bigger than 1-7/16") (Equal to 37 mm in Metric)
- 1-1/2" (1-1/2" is one size smaller than 1-9/16") (1-9/16" is one size bigger than 1-1/2") (Equal to 39 mm in Metric)
- 1-9/16" (1-9/16" is one size smaller than 1-5/8") (1-5/8" is one size bigger than 1-9/16") (Equal to 40 mm in Metric)
- 1-5/8" (1-5/8" is one size smaller than 1-11/16") (1-11/16" is one size bigger than 1-5/8") (Equal to 42 mm in Metric)
- 1-11/16" (1-11/16" is one size smaller than 1-3/4") (1-3/4" is one size bigger than 1-11/16") (Equal to 43 mm in Metric)
- 1-3/4" (1-3/4" is one size smaller than 1-13/16") (1-13/16" is one size bigger than 1-3/4") (Equal to 45 mm in Metric)
- 1-13/16" (1-13/16" is one size smaller than 1-7/8") (1-7/8" is one size bigger than 1-13/16") (Equal to 47 mm in Metric)
- 1-7/8" (1-7/8" is one size smaller than 1-15/16") (1-15/16" is one size bigger than 1-7/8") (Equal to 48 mm in Metric)
- 1-15/16" (1-15/16" is one size smaller than 2") (2" is one size bigger than 1-15/16") (Equal to 50 mm in Metric)
- 2" (2" is the largest SAE wrench size) (Equal to 51 mm in Metric)
Common Bolt Sizes & Matching Wrenches
Knowing which wrench fits which bolt can save you time and frustration. Below is a guide to common SAE and Metric bolt sizes along with the correct wrench sizes to use.
| Bolt Size | Wrench Size (SAE) | Wrench Size (Metric) |
|---|---|---|
| 1/4"-20 | 7/16" | 11 or 12 mm |
| 5/16"-18 | 1/2" | 13 mm |
| 3/8"-16 | 9/16" | 14 mm |
| 7/16"-14 | 5/8" | 16 mm |
| 1/2"-13 | 3/4" | 19 mm |
| 5/8"-11 | 15/16" | 24 mm |
| 3/4"-10 | 1-1/8" | 29 mm |
| 7/8"-9 | 1-5/16" | 34 mm |
| 1"-8 | 1-1/2" | 38 mm |
As you can see, many metric and SAE sizes overlap. If you’re in a pinch, some close metric equivalents can be used on SAE bolts and vice versa.
Types of Wrenches and Sockets
In addition to knowing the size you need, it's important to understand the types of wrenches and sockets available. Common types include:
- Standard Wrenches: These are the traditional, open ended wrenches you're probably used to seeing in any toolkit.
- Box Wrenches: These are closed loop wrenches that fit securely around the nut or bolt, providing more torque and reducing the chance of stripping.
- Socket Wrenches: These are used with interchangeable sockets and allow for a greater range of motion, making them ideal for tight spaces.
- Torque Wrenches: A special tool that ensures fasteners are tightened to a specific torque value. This is particularly important for automotive work.
Socket and Wrench Sizes and Use Case
The socket and wrench sizes listed above are standard for most mechanical and automotive tasks. Here's a breakdown of where these sizes are typically used:
- Small SAE Sizes (1/4" to 1/2"): These sizes are commonly used in precision applications, such as small machinery, electronics, and automotive tasks like bicycle and motorcycle maintenance.
- Medium SAE Sizes (9/16" to 1-1/4"): These sizes are frequently found in automotive work and general mechanical tasks. Many hand tools, like ratchets and wrenches, are designed for these sizes.
- Large SAE Sizes (1-5/16" to 2"): These larger sizes are typically used for heavy machinery, large automotive applications (such as truck engines), and industrial equipment.
In addition to size, the type of measurement system also plays a crucial role in selecting the right tools:
- SAE (Society of Automotive Engineers): This system is primarily used in American-made products and vehicles.
- Metric: More common in European, Asian, and modern industrial machinery, the Metric system has gained widespread use in recent years.
Tool History & Fun Facts
Ever wondered where wrench sizes came from? Here are some interesting facts about SAE and Metric measurements:
- The SAE system was developed primarily for American made vehicles and machinery.
- Metric tools became widely used in the U.S. after the 1980s, as foreign car manufacturers gained popularity.
- The adjustable wrench (also known as a "Crescent Wrench") was invented in 1892 by Johan Petter Johansson.
- The phrase "righty tighty, lefty loosey" is a mnemonic for remembering the standard threading direction.
- Some aircraft use a mix of SAE and Metric fasteners, making proper tool selection critical for aviation mechanics.
Next time you pick up a wrench, remember that you're holding a piece of engineering history!
Conclusion
Whether you're working with SAE or Metric tools, this wrench and socket sizes conversion chart can be your best friend when it comes to getting the right size every time. It saves you time, eliminates confusion, and ensures your project stays on track. Happy wrenching!