#55 drill size
A #55 drill is 0.0520 in (1.32 mm). It sits between #56 and #54 in the number series; the nearest metric drill is 1.3 mm.
#55 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 |
|---|---|---|---|---|
| 1.3 mm | 0.0512" | −0.021 mm | −0.0008" | Smaller |
| 1.35 mm | 0.0531" | +0.029 mm | +0.0011" | 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 #55 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 |
|---|---|---|---|
| M1.6 × 0.35 | 1.25 mm | 61 % | Hard, tough metals |
Number drill index
Every size in the series, holes drawn to scale.
Common questions
What size is a #55 drill?
A #55 drill is 0.0520 in, which is 1.32 mm (1.3208 mm exactly).
What is the metric equivalent of a #55 drill?
The nearest metric drill is 1.3 mm, 0.021 mm smaller. The other close size is 1.35 mm.
What thread can I tap with a #55 drill?
It leaves about 61 % thread in M1.6 × 0.35.
Which fractional drill is closest to #55?
3/64 in (0.0469 in) is the closest, 0.0051 in smaller.