#16 drill size
A #16 drill is 0.1770 in (4.50 mm). It is the standard tap drill for #12-24 UNC; the nearest metric drill is 4.5 mm.
#16 at a glance
Decimal, metric and the nearest sizes in the other series.
- Decimal inch
- 0.1770"
- Millimetres
- 4.50 mm 4.4958
- Nearest metric drill
- 4.5 mm +0.004 mm
- Nearest fractional
- 11/64" 0.1719", −0.0051"
- Hole area
- 0.0246 in² 15.87 mm²
- Tap drill for
- #12-24 UNC
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 |
|---|---|---|---|---|
| 4.4 mm | 0.1732" | −0.096 mm | −0.0038" | Smaller |
| 4.5 mm | 0.1772" | +0.004 mm | +0.0002" | 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 #16 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).
| Thread | Standard drill | Thread with this drill | Suits |
|---|---|---|---|
| #12-24 UNC | #16 | 72 % | Standard drill |
| M5 × 0.5 | 4.5 mm | 78 % | Soft metals, plastics |
| #12-28 UNF | #14 | 84 % | Soft metals, plastics |
Clearance for screws and bolts
Bolts and screws a #16 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 |
|---|---|---|---|---|
| #5 screw | 0.1250" | 0.0520" | 0.0260" | – |
| #6 screw | 0.1380" | 0.0390" | 0.0195" | – |
| M4 bolt | 4 mm | 0.50 mm | 0.25 mm | Close fit (close 4.3, normal 4.5 mm) |
| #8 screw | 0.1640" | 0.0130" | 0.0065" | – |
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 #16 drill?
A #16 drill is 0.1770 in, which is 4.50 mm (4.4958 mm exactly).
What is the metric equivalent of a #16 drill?
The nearest metric drill is 4.5 mm, 0.004 mm larger. The other close size is 4.4 mm.
What tap uses a #16 drill?
A #16 drill is the standard tap drill for #12-24 UNC (about 72 % thread).
Which fractional drill is closest to #16?
11/64 in (0.1719 in) is the closest, 0.0051 in smaller.
What does a #16 drill clear?
It clears a #8 screw with 0.0130" total clearance (0.0065" per side).