This chart provides a quick reference to US machine screw diameters, including decimal and metric equivalents, nearest fractional sizes, and standard thread pitches. Whether you’re selecting hardware for a prototype or replacing components in existing equipment, having a reliable machine screw size chart on hand can save time and prevent costly errors. Below, you’ll find a clear breakdown of machine screw thread sizes from #0 to 1/2″, aligned with both coarse and fine thread pitch standards commonly used in the U.S.
| Size # | Decimal (in) | Metric (mm) | Nearest Fraction | TPI Coarse | TPI Fine |
|---|---|---|---|---|---|
| #0 | 0.0600 | 1.52 | 1/16″ | 80 | – |
| #1 | 0.0730 | 1.85 | 5/64″ | 64 | 72 |
| #2 | 0.0860 | 2.18 | 3/32″ | 56 | 64 |
| #3 | 0.0990 | 2.51 | 7/64″ | 48 | 56 |
| #4 | 0.1120 | 2.84 | 7/64″ | 40 | 48 |
| #5 | 0.1250 | 3.18 | 1/8″ | 40 | 44 |
| #6 | 0.1380 | 3.51 | 9/64″ | 32 | 40 |
| #8 | 0.1640 | 4.17 | 5/32″ | 32 | 36 |
| #10 | 0.1900 | 4.83 | 3/16″ | 24 | 32 |
| #12 | 0.2160 | 5.49 | 7/32″ | 24 | 28 |
| 1/4″ | 0.2500 | 6.35 | 1/4″ | 20 | 28 |
| 5/16″ | 0.3125 | 7.94 | 5/16″ | 18 | 24 |
| 3/8″ | 0.3750 | 9.53 | 3/8″ | 16 | 24 |
| 7/16″ | 0.4375 | 11.11 | 7/16″ | 14 | 20 |
| 1/2″ | 0.5000 | 12.70 | 1/2″ | 13 | 20 |
Find machine screws and a huge array of other fasteners at MISUMI USA. Need help figuring out what size and type of fastener is best for your needs? Please contact our team of product experts. Interested in more articles with helpful charts, and calculators for projects and engineers? Check out more of our blog – MechLab Blog.