Metric to Inch Bolt Conversion Chart
Approximate conversions between metric and imperial bolt sizes, wrench sizes, and thread pitches.
| Metric | Inch (approx) | Wrench (mm) | Wrench (in) |
|---|---|---|---|
| M4 | #8 (0.164 in) | 7 mm | 9/32 |
| M5 | #10 (0.190 in) | 8 mm | 5/16 |
| M6 | 1/4 in | 10 mm | 3/8 |
| M8 | 5/16 in | 13 mm | 1/2 |
| M10 | 3/8 in | 17 mm | 11/16 |
| M12 | 1/2 in | 19 mm | 3/4 |
| M16 | 5/8 in | 24 mm | 15/16 |
| M20 | 3/4 in | 30 mm | 1-3/16 |
These are approximate — a metric and inch fastener never interchange. Match the actual thread and grade.
Printable PDF
Download the printer-friendly Metric to Inch Bolt Conversion Chart as a free PDF — perfect for the shop wall or toolbox.
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