Shop reference
SAE to metric socket chart
Missing a size? These are the swaps that actually work. "Same fit" means the sizes are within about 0.15 mm. "A bit loose" means the socket is slightly bigger than the bolt head and will work in a pinch, but don't use it on a rounded or very tight fastener. A socket smaller than the bolt head won't go on at all.
Have an SAE bolt, need a metric socket
| SAE size | In mm | Metric socket that fits |
|---|---|---|
| 1/4" | 6.35 | No close match |
| 5/16" | 7.94 | 8 mm, same fit |
| 11/32" | 8.73 | 9 mm, a bit loose |
| 3/8" | 9.53 | No close match |
| 7/16" | 11.11 | 11 mm, same fit |
| 1/2" | 12.70 | 13 mm, a bit loose |
| 9/16" | 14.29 | No close match |
| 5/8" | 15.88 | 16 mm, same fit |
| 11/16" | 17.46 | No close match |
| 3/4" | 19.05 | 19 mm, same fit |
| 13/16" | 20.64 | 21 mm, a bit loose |
| 7/8" | 22.23 | No close match |
| 15/16" | 23.81 | 24 mm, a bit loose |
| 1" | 25.40 | No close match |
| 1-1/16" | 26.99 | 27 mm, same fit |
| 1-1/8" | 28.58 | No close match |
| 1-1/4" | 31.75 | 32 mm, a bit loose |
Have a metric bolt, need an SAE socket
| Metric size | In inches | SAE socket that fits |
|---|---|---|
| 4 mm | 0.157" | No close match |
| 5 mm | 0.197" | No close match |
| 5.5 mm | 0.217" | No close match |
| 6 mm | 0.236" | 1/4", a bit loose |
| 7 mm | 0.276" | No close match |
| 8 mm | 0.315" | 5/16", same fit |
| 9 mm | 0.354" | No close match |
| 10 mm | 0.394" | No close match |
| 11 mm | 0.433" | 7/16", same fit |
| 12 mm | 0.472" | No close match |
| 13 mm | 0.512" | No close match |
| 14 mm | 0.551" | 9/16", a bit loose |
| 15 mm | 0.591" | No close match |
| 16 mm | 0.630" | 5/8", same fit |
| 17 mm | 0.669" | No close match |
| 18 mm | 0.709" | No close match |
| 19 mm | 0.748" | 3/4", same fit |
| 20 mm | 0.787" | No close match |
| 21 mm | 0.827" | No close match |
| 22 mm | 0.866" | 7/8", a bit loose |
| 23 mm | 0.906" | No close match |
| 24 mm | 0.945" | No close match |
| 27 mm | 1.063" | 1-1/16", same fit |
| 30 mm | 1.181" | No close match |
| 32 mm | 1.260" | No close match |
| 34 mm | 1.339" | No close match |
| 36 mm | 1.417" | No close match |
Keep this chart in your pocket
Garage Brain has this chart built in, along with torque, pressure, fluid and temperature converters. It also remembers which sockets every job on your vehicles takes.