Socket Size Chart
Socket sizes are available in both SAE (imperial) and metric measurements. The chart below lists common socket sizes from 5/32 inch to 1 inch, with their closest metric equivalents and the appropriate drive size. Knowing the right socket size prevents rounding bolt heads and makes any repair job faster and safer.
| SAE Size | Metric Equivalent | Drive Size | Common Use |
|---|---|---|---|
| 5/32" | 4 mm | 1/4-inch | Small electronics, instrument screws |
| 3/16" | 5 mm | 1/4-inch | Small machine screws |
| 7/32" | 5.5 mm | 1/4-inch | Light equipment |
| 1/4" | 6 mm | 1/4-inch | Small bolts, appliance repair |
| 9/32" | 7 mm | 1/4-inch | Automotive trim, small bolts |
| 5/16" | 8 mm | 3/8-inch | Common automotive fasteners |
| 11/32" | 9 mm | 3/8-inch | Small engine work |
| 3/8" | 10 mm | 3/8-inch | Most common automotive size |
| 7/16" | 11 mm | 3/8-inch | Automotive, general repair |
| 1/2" | 13 mm | 3/8-inch | 1/2-inch bolts, automotive |
| 9/16" | 14 mm | 3/8-inch | Brake components, suspension |
| 5/8" | 16 mm | 1/2-inch | Larger automotive bolts |
| 11/16" | 17 mm | 1/2-inch | Wheel lug nuts (some vehicles) |
| 3/4" | 19 mm | 1/2-inch | Wheel lug nuts, structural bolts |
| 13/16" | 21 mm | 1/2-inch | Spark plugs, large fasteners |
| 7/8" | 22 mm | 1/2-inch | Heavy equipment, large bolts |
| 15/16" | 24 mm | 1/2-inch | Industrial fasteners |
| 1" | 25 mm | 1/2-inch | Heavy-duty structural bolts |
SAE to Metric Conversion Notes
Why You Need Both Sets
SAE and metric sockets are close in size but not interchangeable. Using the wrong system can round off bolt heads, making them much harder to remove. A 1/2-inch socket (12.70 mm) is slightly smaller than a 13 mm socket, and forcing the wrong size damages the fastener. Always match the socket to the bolt system.
Drive Size Guide
The drive size refers to the square opening that connects the socket to the ratchet handle. Use 1/4-inch drive for small, tight spaces like dashboards and electronics. Use 3/8-inch drive for most general automotive and home repair work. Use 1/2-inch drive for larger fasteners and when you need more torque, such as lug nuts and suspension bolts.
The 10mm Socket
The 10 mm socket (equivalent to 3/8 inch SAE) is the most commonly used socket in automotive repair. It fits a wide range of fasteners found on Japanese, Korean, and European vehicles. It is also the socket most frequently lost in home garages, so consider buying extras.