Overview
Technical specifications for M3 metric and #4-40 UNC imperial fasteners.
Comparison Table
| Standard | Size | Diameter (mm) | Pitch / TPI |
|---|---|---|---|
| Metric | M3 | 3.00 mm | 0.50 mm |
| Imperial | #4-40 UNC | 2.84 mm | 40 TPI |
FAQ
Is M3 the same as #4-40?
No, they use different thread standards and are not interchangeable.
Source Standard
ISO 261 / ANSI B1.1