SOCKET &
WRENCH
CONVERTER
SAE ↔ METRIC SOCKET SIZE REFERENCE
SAE to Metric Socket Converter
Convert SAE socket sizes to metric and metric socket sizes to their closest SAE equivalents. Find exact millimeter measurements and common socket sizes quickly.
Find Your Socket Size
Select a socket size below to see the exact mathematical conversion and the closest commonly used socket size.
Common SAE Socket Conversions
These are common SAE socket sizes and their exact millimeter measurements. The metric size shown is the closest common metric socket, not necessarily an exact dimensional match.
| SAE Socket | Exact mm | Closest Metric |
|---|---|---|
| 1/4" | 6.35 mm | 6 mm |
| 5/16" | 7.9375 mm | 8 mm |
| 11/32" | 8.73125 mm | 9 mm |
| 3/8" | 9.525 mm | 10 mm |
| 7/16" | 11.1125 mm | 11 mm |
| 1/2" | 12.7 mm | 13 mm |
| 9/16" | 14.2875 mm | 14 mm |
| 5/8" | 15.875 mm | 16 mm |
| 11/16" | 17.4625 mm | 17 mm |
| 3/4" | 19.05 mm | 19 mm |
| 13/16" | 20.6375 mm | 21 mm |
| 7/8" | 22.225 mm | 22 mm |
| 15/16" | 23.8125 mm | 24 mm |
| 1" | 25.4 mm | 25 mm |
| 1 1/16" | 26.9875 mm | 27 mm |
| 1 1/8" | 28.575 mm | 29 mm |
| 1 3/16" | 30.1625 mm | 30 mm |
| 1 1/4" | 31.75 mm | 32 mm |
| 1 5/16" | 33.3375 mm | 33 mm |
| 1 3/8" | 34.925 mm | 35 mm |
| 1 7/16" | 36.5125 mm | 37 mm |
| 1 1/2" | 38.1 mm | 38 mm |
SAE Socket to Metric Conversions
What is a 1/4 inch socket in metric?
A 1/4 inch socket is exactly 6.35 mm. The closest common metric socket is 6 mm.
What is a 3/8 socket in metric?
A 3/8 inch socket is exactly 9.525 mm. The closest common metric socket is 10 mm.
What is a 1/2 inch socket in metric?
A 1/2 inch socket is exactly 12.7 mm. The closest common metric socket is 13 mm.
What is a 9/16 socket in metric?
A 9/16 inch socket is exactly 14.2875 mm. The closest common metric socket is 14 mm.
What is a 5/8 socket in metric?
A 5/8 inch socket is exactly 15.875 mm. The closest common metric socket is 16 mm.
What is a 3/4 socket in metric?
A 3/4 inch socket is exactly 19.05 mm. The closest common metric socket is 19 mm.
What is a 13/16 socket in metric?
A 13/16 inch socket is exactly 20.6375 mm. The closest common metric socket is 21 mm.
What is a 7/8 socket in metric?
A 7/8 inch socket is exactly 22.225 mm. The closest common metric socket is 22 mm.
What is a 1 inch socket in metric?
A 1 inch socket is exactly 25.4 mm. The closest common metric socket is 25 mm.
What is a 1 1/16 socket in metric?
A 1 1/16 inch socket is exactly 26.9875 mm. The closest common metric socket is 27 mm.
What is a 1 1/8 socket in metric?
A 1 1/8 inch socket is exactly 28.575 mm. The closest common metric socket is 29 mm.
What is a 1 1/4 socket in metric?
A 1 1/4 inch socket is exactly 31.75 mm. The closest common metric socket is 32 mm.
Common Metric Socket to SAE Equivalents
Metric sockets do not always have an exact SAE equivalent. These results show the closest common SAE size based on actual dimensions.
| Metric | Closest SAE | Exact SAE Size |
|---|---|---|
| 6 mm | 1/4" | 6.35 mm |
| 7 mm | 1/4" | 6.35 mm |
| 8 mm | 5/16" | 7.9375 mm |
| 9 mm | 11/32" | 8.73125 mm |
| 10 mm | 3/8" | 9.525 mm |
| 11 mm | 7/16" | 11.1125 mm |
| 12 mm | 1/2" | 12.7 mm |
| 13 mm | 1/2" | 12.7 mm |
| 14 mm | 9/16" | 14.2875 mm |
| 15 mm | 9/16" | 14.2875 mm |
| 16 mm | 5/8" | 15.875 mm |
| 17 mm | 11/16" | 17.4625 mm |
| 18 mm | 11/16" | 17.4625 mm |
| 19 mm | 3/4" | 19.05 mm |
| 20 mm | 13/16" | 20.6375 mm |
| 21 mm | 13/16" | 20.6375 mm |
| 22 mm | 7/8" | 22.225 mm |
| 23 mm | 7/8" | 22.225 mm |
| 24 mm | 15/16" | 23.8125 mm |
| 25 mm | 1" | 25.4 mm |
| 26 mm | 1" | 25.4 mm |
| 27 mm | 1 1/16" | 26.9875 mm |
| 28 mm | 1 1/8" | 28.575 mm |
| 29 mm | 1 1/8" | 28.575 mm |
| 30 mm | 1 3/16" | 30.1625 mm |
| 31 mm | 1 1/4" | 31.75 mm |
| 32 mm | 1 1/4" | 31.75 mm |
| 33 mm | 1 5/16" | 33.3375 mm |
| 34 mm | 1 5/16" | 33.3375 mm |
| 35 mm | 1 3/8" | 34.925 mm |
| 36 mm | 1 7/16" | 36.5125 mm |
| 37 mm | 1 7/16" | 36.5125 mm |
| 38 mm | 1 1/2" | 38.1 mm |
Socket Wrench Conversion Questions
Are SAE and metric sockets interchangeable?
Some SAE and metric sizes are very close in physical dimensions, but they are not automatically interchangeable. Use the correct socket size whenever possible to reduce the chance of rounding or damaging the fastener.
Is 13/16 the same as 21 mm?
No. A 13/16 inch socket is exactly 20.6375 mm, while a 21 mm socket measures 21 mm. They are close in size, but they are not identical.
Is 7/8 the same as 22 mm?
No. A 7/8 inch socket is exactly 22.225 mm. A 22 mm socket is slightly smaller.
Is 1 inch the same as 25 mm?
No. One inch equals exactly 25.4 mm. A 25 mm socket is therefore slightly smaller.
What is the difference between SAE and metric?
SAE socket sizes are traditionally measured in inches and commonly expressed as fractions. Metric socket sizes are measured in millimeters.
How do I know which socket to use?
Use the socket that fits the fastener securely without excessive play. If the fastener is marked or specified for a particular size, use that size rather than substituting a near-equivalent socket.
SAE-to-metric values shown here are dimensional conversions. A "closest" socket is not necessarily interchangeable with the original size. When working on a vehicle, machine, or other fastener, use the specified socket size whenever possible.