mm to inches chart
This covers the metric sizes that come up most with drill bits, sockets, bolts and lumber. The fraction columns show the nearest 16th (what you'd read off a tape measure) and the nearest 64th (closer to drill-bit accuracy). 1 inch is exactly 25.4 mm.
| mm | Decimal in | Nearest 1/16 | Nearest 1/64 |
|---|---|---|---|
| 1 mm | 0.0394" | 1/16" | 3/64" |
| 2 mm | 0.0787" | 1/16" | 5/64" |
| 3 mm | 0.1181" | 1/8" | 1/8" |
| 4 mm | 0.1575" | 3/16" | 5/32" |
| 5 mm | 0.1969" | 3/16" | 13/64" |
| 6 mm | 0.2362" | 1/4" | 15/64" |
| 8 mm | 0.3150" | 5/16" | 5/16" |
| 10 mm | 0.3937" | 3/8" | 25/64" |
| 12 mm | 0.4724" | 1/2" | 15/32" |
| 13 mm | 0.5118" | 1/2" | 33/64" |
| 15 mm | 0.5906" | 9/16" | 19/32" |
| 16 mm | 0.6299" | 5/8" | 5/8" |
| 19 mm | 0.7480" | 3/4" | 3/4" |
| 20 mm | 0.7874" | 13/16" | 25/32" |
| 22 mm | 0.8661" | 7/8" | 55/64" |
| 25 mm | 0.9843" | 1" | 63/64" |
| 30 mm | 1.1811" | 19/16" | 19/16" |
| 32 mm | 1.2598" | 5/4" | 81/64" |
| 38 mm | 1.4961" | 3/2" | 3/2" |
| 40 mm | 1.5748" | 25/16" | 101/64" |
| 50 mm | 1.9685" | 31/16" | 63/32" |
| 75 mm | 2.9528" | 47/16" | 189/64" |
| 100 mm | 3.9370" | 63/16" | 63/16" |
For any other size, use the converter.