#23 drill size
A #23 drill is 0.1540 in (3.91 mm). It sits between #24 and #22 in the number series; the nearest metric drill is 3.9 mm.
#23 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 |
|---|---|---|---|---|
| 3.9 mm | 0.1535" | −0.012 mm | −0.0005" | Smaller |
| 4.0 mm | 0.1575" | +0.088 mm | +0.0035" | 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 #23 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 |
|---|---|---|---|
| #10-24 UNC | #25 | 67 % | Good in steel |
Clearance for screws and bolts
Bolts and screws a #23 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 |
|---|---|---|---|---|
| #3 screw | 0.0990" | 0.0550" | 0.0275" | – |
| #4 screw | 0.1120" | 0.0420" | 0.0210" | – |
| #5 screw | 0.1250" | 0.0290" | 0.0145" | – |
| M3.5 bolt | 3.5 mm | 0.41 mm | 0.21 mm | Normal fit (normal 3.9, loose 4.2 mm) |
| #6 screw | 0.1380" | 0.0160" | 0.0080" | – |
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 #23 drill?
A #23 drill is 0.1540 in, which is 3.91 mm (3.9116 mm exactly).
What is the metric equivalent of a #23 drill?
The nearest metric drill is 3.9 mm, 0.012 mm smaller. The other close size is 4.0 mm.
What thread can I tap with a #23 drill?
It leaves about 67 % thread in #10-24 UNC.
Which fractional drill is closest to #23?
5/32 in (0.1562 in) is the closest, 0.0023 in larger.
What does a #23 drill clear?
It clears a #6 screw with 0.0160" total clearance (0.0080" per side).