#42 drill size
A #42 drill is 0.0935 in (2.37 mm). It is the standard tap drill for #4-48 UNF; the nearest metric drill is 2.35 mm.
#42 at a glance
Decimal, metric and the nearest sizes in the other series.
Nearest metric drills
Metric drills step by 0.05 mm below 3 mm and by 0.1 mm from 3 mm. Difference is metric minus inch size.
| Metric drill | Inch | Difference | In inches | Hole |
|---|---|---|---|---|
| 2.35 mm | 0.0925" | −0.025 mm | −0.0010" | Smaller |
| 2.4 mm | 0.0945" | +0.025 mm | +0.0010" | Larger |
Nearby inch drills
The next size down and up in each inch series, so you can pick a substitute from the drawer.
Threads a #42 drill can tap
Threads from the tap tables on this site that this drill can tap, with the thread percentage it leaves (55–85 % shown).
Clearance for screws and bolts
Bolts and screws a #42 hole clears, with the diametral clearance and the gap each side. Metric sizes are compared with ISO 273.
| Fastener | Diameter | Clearance | Per side | ISO 273, metric only |
|---|---|---|---|---|
| #1 screw | 0.0730" | 0.0205" | 0.0103" | – |
| M2 bolt | 2 mm | 0.37 mm | 0.19 mm | Close fit (close 2.2, normal 2.4 mm) |
| #2 screw | 0.0860" | 0.0075" | 0.0038" | – |
Inch clearance is the drill size minus the basic major diameter. A drilled hole usually cuts slightly oversize.
Number drill index
Every size in the series, holes drawn to scale.
Common questions
What size is a #42 drill?
A #42 drill is 0.0935 in, which is 2.37 mm (2.3749 mm exactly).
What is the metric equivalent of a #42 drill?
The nearest metric drill is 2.35 mm, 0.025 mm smaller. The other close size is 2.4 mm.
What tap uses a #42 drill?
A #42 drill is the standard tap drill for #4-48 UNF (about 68 % thread).
Which fractional drill is closest to #42?
3/32 in (0.0938 in) is the closest, 0.0003 in larger.
What does a #42 drill clear?
It clears a #2 screw with 0.0075" total clearance (0.0038" per side).