M6 vs 1/4-20 UNC Screw Size Chart
Overview
Technical data for M6 metric and 1/4-20 UNC imperial fasteners. These are often used in similar applications, but their dimensions and threads differ significantly.
Comparison Table
| Standard | Size | Diameter (mm) | Pitch / TPI | Tap Drill |
|---|---|---|---|---|
| Metric | M6 | 6.00 mm | 1.00 mm | 5.0 mm |
| Imperial | 1/4”-20 UNC | 6.35 mm | 20 TPI | 5.1 mm (#7) |
FAQ
Is M6 interchangeable with 1/4-20?
No. While they look similar, the 1/4”-20 screw (6.35 mm) is physically larger than the M6 screw (6.00 mm). Furthermore, the thread pitches (1.00 mm vs 1.27 mm equivalent) will not mesh, leading to immediate thread damage.
Source Standard
ISO 261 / ASME B1.1