What Dose SAE Socket Size Mean
You may often find that some American sockets are based on the SAE standard. They use inches and fractions of inches to distinguish the socket size. Common sizes include: 1/4″, 5/16″, 3/8″, 1/2″, 9/16″, 5/8″, 3/4″, and 1″. So what is the SAE standard socket? SAE socket size is a standard set by the American Society of Automotive Engineers. So if you live in the United States or want to repair some American-made vehicles, then it is very necessary to learn more about it.
What Dose Metric Socket Size Mean
If you need to repair an imported vehicle or instrument, you might find that your SAE socket won’t fit many bolts or nuts. At this time, you need another type of socket – a metric socket. The size of the metric socket is often marked on the outside of the socket in the form of “M+number”. M stands for millimeter. Common metric socket sizes are 4mm, 8mm, 10mm, 12mm, and 14mm. This is a more common measurement system used worldwide.
SAE to Metric Conversion Chart
In actual work, we often encounter bolts and nuts of various different standards: some are SAE sizes and some are metric sizes. While some dimensions are very similar, they are not completely interchangeable. Choosing the wrong socket can easily cause a screw to slip, damaging tools or work pieces. This comparison chart can help you quickly find the right size and improve your work efficiency.
| SAE（inch） | Metric（mm） |
| 1/8″ | 3.175 mm |
| 5/32″ | 3.968 mm |
| 3/16″ | 4.762 mm |
| 7/32″ | 5.556 mm |
| 1/4″ | 6.350 mm |
| 5/16″ | 7.938 mm |
| 3/8″ | 9.525 mm |
| 7/16″ | 11.113 mm |
| 1/2″ | 12.7 mm |
| 9/16″ | 14.287 mm |
| 5/8″ | 15.875 mm |
| 11/16″ | 17.463 mm |
| 3/4″ | 19.05 mm |
| 13/16″ | 20.638 mm |
| 7/8″ | 22.225 mm |
| 15/16″ | 23.813 mm |
| 1″ | 25.4 mm |
Socket Wrench Drive Sizes Chart
When you’re actually removing a nut, you’ll need to attach a socket to the drive head of a ratchet or impact wrench and use the wrench to turn the nut. The drive head sizes are all in inches. The larger the drive size, the greater the torque it can withstand. As you can imagine, different sized drive heads require different sockets. This chart lists several common drive sizes. Find the appropriate socket below, whether SAE or metric.
| Drive Size | Common Socket Range (SAE) | Common Socket Range (Metric) |
| 1/4″ | 3/16″ to 9/16″ | 4mm to 14mm |
| 3/8″ | 1/4″ to 7/8″ | 6mm to 22mm |
| 1/2″ | 3/8″ to 1-1/4″ | 10mm to 32mm |
| 3/4″ | 7/8″ to 2-1/4″ | 19mm to 50mm |
| 1″ | 1″ to 4″ | 24mm to 100mm |
Most Common Socket Sizes and Their Uses
Common socket sizes are generally divided into 1/4″-5/16″ (6mm-8mm), 3/8″-7/16″ (9mm -11mm), 1/2″-5/8″ (13mm-16mm), , and 3/4″-1″ (19mm-25mm). Among them, 3/8″-7/16″ is the most popular size and widely used in automobile/motorcycle maintenance,plumbing repairs, home appliance installation, and light industrial repairs.
If you want to do some home repairs or DIY jobs, you can choose small to medium-sized socketsfrom 1/4″to 5/16″. Which can help you better complete precise work,such as removing /installing nuts on bicycles, assembling furniture parts, etc., and you can keep a spare set at home.
Normally, large size sockets are good helper for professional engineers, widely application to heavy duty operations. Sockets with sizes 1/2″-5/8″ are suitable for inspecting and repairing production lines, mechanical equipment and agricultural machine. When you need to remove and install higherstrength fasteners, such as installing heavy machinery or repairing ships, 3/4″-1″ sockets are your ultimate choice.
How to Choose the Right Socket Size
Now that you know the two types of socket sizes and the wrench drive sizes correspond to them, is there a quick guide to finding the right tool? Yes, there is.
First, check whether the length is marked on the bolt/nut. If it is marked with 1/8″, then you need to use a 1/8″ or 3mm socket to adapt it. If there is no marking on the bolt or nut or the marking is no longer recognizable, we need a vernier caliper (the vernier caliper here can also be replaced by other precise measuring tools) to measure the head of the bolt/nut, and then find the socket with the most appropriate size based on the measured results. Then, install the socket onto the bolt/nut. If it doesn’t fit, the socket will become loose or won’t install. This means you need to change the model or there’s a lack of compatible models. Finally, if the socket fits the bolt/nut, you can find the wrench drive size that matches the socket in the table above, install the socket on the ratchet wrench, and you can start to work.
FAQ
Are 1/4” sockets the same as 6mm?
No, they’re not. Because these two sockets use different units, we must first convert them to standard units. Referring to the table in the article, 1/4″ can be converted to 6.35mm. Otherwise, you can directly measure the diameter of a 1/4″ socket with a ruler, which measures approximately 6.3mm. Both methods indicate that there is a difference between a 1/4″ socket and a 6mm socket, and they cannot be matched.
Are SAE and imperial the same?
No, they are different. SAE is the US standard for lengths in feet and inches for tools like bolts, nuts, and sockets. While they appear to be in feet and inches, SAE is a narrower term, referring only to lengths in feet and inches used in machine tools. The Imperial system encompasses all the length, volume, and weight measurements you see in feet, inches, and pounds.
