#19 drill size
A #19 drill is 0.1660 in (4.22 mm). It sits between #20 and #18 in the number series; the nearest metric drill is 4.2 mm.
#19 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 |
|---|---|---|---|---|
| 4.2 mm | 0.1654" | −0.016 mm | −0.0006" | Smaller |
| 4.3 mm | 0.1693" | +0.084 mm | +0.0033" | 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 #19 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 |
|---|---|---|---|
| M5 × 0.8 | 4.2 mm | 75 % | Soft metals, plastics |
| #10-32 UNF | #21 | 59 % | Hard, tough metals |
Clearance for screws and bolts
Bolts and screws a #19 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 |
|---|---|---|---|---|
| #4 screw | 0.1120" | 0.0540" | 0.0270" | – |
| #5 screw | 0.1250" | 0.0410" | 0.0205" | – |
| #6 screw | 0.1380" | 0.0280" | 0.0140" | – |
| M4 bolt | 4 mm | 0.22 mm | 0.11 mm | Tighter than close fit (4.3 mm) |
| #8 screw | 0.1640" | 0.0020" | 0.0010" | – |
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 #19 drill?
A #19 drill is 0.1660 in, which is 4.22 mm (4.2164 mm exactly).
What is the metric equivalent of a #19 drill?
The nearest metric drill is 4.2 mm, 0.016 mm smaller. The other close size is 4.3 mm.
What thread can I tap with a #19 drill?
It leaves about 75 % thread in M5 × 0.8 and 59 % in #10-32 UNF.
Which fractional drill is closest to #19?
11/64 in (0.1719 in) is the closest, 0.0059 in larger.
What does a #19 drill clear?
It clears a #8 screw with 0.0020" total clearance (0.0010" per side).