#78 drill size
A #78 drill is 0.0160 in (0.41 mm). It sits between #79 and #77 in the number series; the nearest metric drill is 0.4 mm.
#78 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 |
|---|---|---|---|---|
| 0.4 mm | 0.0157" | −0.006 mm | −0.0003" | Smaller |
| 0.45 mm | 0.0177" | +0.044 mm | +0.0017" | 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 #78 drill can tap
No thread in the tap tables on this site falls between 55 and 85 % thread with this drill, so it is not a useful tap drill for them. Drills this size are mostly used for clearance, pilot and pin holes.
Number drill index
Every size in the series, holes drawn to scale.
Common questions
What size is a #78 drill?
A #78 drill is 0.0160 in, which is 0.41 mm (0.4064 mm exactly).
What is the metric equivalent of a #78 drill?
The nearest metric drill is 0.4 mm, 0.006 mm smaller. The other close size is 0.45 mm.
Which fractional drill is closest to #78?
1/64 in (0.0156 in) is the closest, 0.0004 in smaller.