MAN4MACHINE← All thread specs
Straight
UNEF
Unified National Extra Fine
The extra-fine Unified series, common on instrumentation, aerospace, and AN/JIC-adjacent fittings where thin-wall parts need a shallow thread and a fine adjustment pitch.
- Standard
- ASME B1.1
- Flank angle
- 60° included
- Sealing
- None inherent -- typically paired with an O-ring or AN-style flare, not a thread seal.
Thread profile
A 60° included flank angle with a flat-truncated crest and root -- the single fastest way to tell a Unified/American pipe thread from the other family by eye.
Cut straight: the pitch diameter is constant along the full thread length, with no taper.
Size chart
| Nominal | TPI | Pitch | Major Ø | Pitch Ø | Minor Ø | Tap drill |
|---|---|---|---|---|---|---|
| 1/4 | 32 | 0.0313" | 0.2500" | 0.2297" | 0.2094" | 7/32" (0.2196") |
| 5/16 | 32 | 0.0313" | 0.3125" | 0.2922" | 0.2719" | 9/32" (0.2821") |
| 3/8 | 32 | 0.0313" | 0.3750" | 0.3547" | 0.3344" | 11/32" (0.3446") |
| 7/16 | 28 | 0.0357" | 0.4375" | 0.4143" | 0.3911" | Y (0.4027") |
| 1/2 | 28 | 0.0357" | 0.5000" | 0.4768" | 0.4536" | 15/32" (0.4652") |
| 9/16 | 24 | 0.0417" | 0.5625" | 0.5354" | 0.5084" | 33/64" (0.5219") |
| 5/8 | 24 | 0.0417" | 0.6250" | 0.5979" | 0.5709" | 37/64" (0.5844") |
| 3/4 | 20 | 0.0500" | 0.7500" | 0.7175" | 0.6850" | 45/64" (0.7013") |
| 7/8 | 20 | 0.0500" | 0.8750" | 0.8425" | 0.8100" | 53/64" (0.8263") |
| 1 | 20 | 0.0500" | 1.0000" | 0.9675" | 0.9350" | 61/64" (0.9513") |
Tap drill calculator
Calculated live
Tap drill7/32"0.2196" calculated · 7/32" (0.2196") nearest standard
- Pitch
- 0.0313"
- Pitch diameter (basic)
- 0.2297"
- Minor diameter (basic)
- 0.2094"
- Clearance drill (normal)
- 9/32" (0.2813")
Comparing against another standard? Open the universal calculator →