#1 drill size
A #1 drill is 0.2280 in (5.79 mm). It is the largest number drill on this chart; the nearest metric drill is 5.8 mm.
#1 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 |
|---|---|---|---|---|
| 5.7 mm | 0.2244" | −0.091 mm | −0.0036" | Smaller |
| 5.8 mm | 0.2283" | +0.009 mm | +0.0003" | 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 #1 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.
Clearance for screws and bolts
Bolts and screws a #1 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 |
|---|---|---|---|---|
| #10 screw | 0.1900" | 0.0380" | 0.0190" | – |
| M5 bolt | 5 mm | 0.79 mm | 0.40 mm | Normal fit (normal 5.5, loose 5.8 mm) |
| #12 screw | 0.2160" | 0.0120" | 0.0060" | – |
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 #1 drill?
A #1 drill is 0.2280 in, which is 5.79 mm (5.7912 mm exactly).
What is the metric equivalent of a #1 drill?
The nearest metric drill is 5.8 mm, 0.009 mm larger. The other close size is 5.7 mm.
Which fractional drill is closest to #1?
15/64 in (0.2344 in) is the closest, 0.0064 in larger.
What does a #1 drill clear?
It clears a #12 screw with 0.0120" total clearance (0.0060" per side).