Fastener Size Converter
| SAE Size |
Diameter (inches) |
Metric Size |
Diameter (mm) |
| #0 | 0.060" | M1.6 | 1.6mm |
| #1 | 0.073" | M1.8 | 1.8mm |
| #2 | 0.086" | M2 | 2.0mm |
| #3 | 0.099" | M2.5 | 2.5mm |
| #4 | 0.112" | M3 | 3.0mm |
| #5 | 0.125" | M3.5 | 3.5mm |
| #6 | 0.138" | M3.5 | 3.5mm |
| #8 | 0.164" | M4 | 4.0mm |
| #10 | 0.190" | M5 | 5.0mm |
| #12 | 0.216" | M5.5 | 5.5mm |
| 1/4" | 0.250" | M6 | 6.0mm |
| 5/16" | 0.3125" | M8 | 8.0mm |
| 3/8" | 0.375" | M10 | 10.0mm |
| 7/16" | 0.4375" | M11 | 11.0mm |
| 1/2" | 0.500" | M12 | 12.0mm |
| 9/16" | 0.5625" | M14 | 14.0mm |
| 5/8" | 0.625" | M16 | 16.0mm |
| 11/16" | 0.6875" | M18 | 18.0mm |
| 3/4" | 0.750" | M20 | 20.0mm |
| 7/8" | 0.875" | M22 | 22.0mm |
| 1" | 1.000" | M24 | 24.0mm |
Wrench Size Converter
| SAE Size (inches) |
Metric Size (mm) |
Best Fit |
| 5/32" | 4mm | Exact |
| 3/16" | 5mm | Approximate |
| 7/32" | 5.5mm | Exact |
| 1/4" | 6mm | Close |
| 9/32" | 7mm | Close |
| 5/16" | 8mm | Close |
| 11/32" | 9mm | Approximate |
| 3/8" | 10mm | Approximate |
| 7/16" | 11mm | Close |
| 1/2" | 13mm | Approximate |
| 9/16" | 14mm | Close |
| 5/8" | 16mm | Close |
| 11/16" | 17mm | Close |
| 3/4" | 19mm | Close |
| 13/16" | 21mm | Approximate |
| 7/8" | 22mm | Close |
| 15/16" | 24mm | Approximate |
| 1" | 25mm | Close |
Drill Size Converter
| SAE Number/Letter |
Decimal (inches) |
Metric (mm) |
| #60 | 0.040" | 1.02mm |
| #55 | 0.052" | 1.32mm |
| #50 | 0.070" | 1.78mm |
| #45 | 0.082" | 2.08mm |
| #40 | 0.098" | 2.49mm |
| #35 | 0.110" | 2.79mm |
| #30 | 0.128" | 3.26mm |
| #25 | 0.150" | 3.80mm |
| #20 | 0.161" | 4.09mm |
| #10 | 0.193" | 4.91mm |
| #1 | 0.228" | 5.79mm |
| A | 0.234" | 5.94mm |
| D | 0.246" | 6.25mm |
| F | 0.257" | 6.53mm |
| I | 0.272" | 6.91mm |
| N | 0.302" | 7.67mm |
| Q | 0.332" | 8.43mm |
| T | 0.358" | 9.09mm |
| X | 0.397" | 10.08mm |
| Z | 0.413" | 10.49mm |
SAE vs. Metric Tips
- SAE (Society of Automotive Engineers) sizes are common in US-made vehicles and older vehicles worldwide.
- Metric sizes are standard in most modern vehicles, especially those made outside the US.
- Using the correct size tool is crucial to avoid stripping fasteners - a close approximation may work in an emergency but should be avoided.
- Most modern mechanic tool sets include both SAE and metric sizes.
- When working on vehicles, pay attention to whether you're dealing with SAE or metric fasteners - mixing them can lead to problems.