#3-48 Tap Drill Size & Thread Specs
Everything for a #3-48 UNC thread on one page: tap drill (#47), clearance holes, wrench and hex key sizes, and the nearest metric thread.
SP-TD-01 · #3-48
#3-48 specs
SizePlate
#3-48 UNC · tap with
#47 drill
.0785″
1.99 mm · 76% thread
- Metric drill
- 2 mm · .0787
- Clearance
- #37 / #35
Thread
- Nominal size
- #3 · 2.51 mm
- Major diameter
- .0990″
- Threads per inch
- 48
- Pitch
- .0208″ · 0.529 mm
- Series
- UNC (coarse)
- UNF version
- #3-56
Drilling
- Tap drill (75%)
- #47 · .0785
- Metric substitute
- 2 mm · .0787
- Tap drill (≈50%)
- #44 · .0860
- Close fit
- #37 · .1040
- Free fit
- #35 · .1100
Nearest metric
- Thread
- M2.5 × 0.45
- Major diameter
- 2.5 mm
- Pitch
- 0.45 mm
- Tap drill
- 2.05 mm
- Interchangeable
- No
Not interchangeable means the threads look close but won't run together: forcing one into the other strips both.
Drill size by thread percentage
Larger drill, less thread, easier tapping. 75% is the usual target.
| Drill | Decimal | mm | Thread |
|---|---|---|---|
| #48 | .0760 | 1.93 | 85% |
| 5/64 | .0781 | 1.98 | 77% |
| #47 | .0785 | 1.99 | 76% |
| 2 mm | .0787 | 2 | 75% |
| 2.05 mm | .0807 | 2.05 | 68% |
| #46 | .0810 | 2.06 | 67% |
| #45 | .0820 | 2.08 | 63% |
| 2.1 mm | .0827 | 2.1 | 60% |
| #44 | .0860 | 2.18 | 48% |
| 2.2 mm | .0866 | 2.2 | 46% |
Neighboring sizes
Questions
What does #3-48 mean?
A #3 nominal diameter with 48 threads per inch. It’s the coarse (UNC) thread for that size; the fine version is #3-56.
Can I use a 2 mm drill instead of #47?
Usually. 2 mm is .0787″ against .0785″ for #47, which changes the thread engagement by a few percent at most. The thread-percentage table above shows exactly how much thread each nearby drill leaves.