#24 drill size
A #24 drill is 0.1520 in (3.86 mm). It sits between #25 and #23 in the number series; the nearest metric drill is 3.9 mm.
#24 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 |
|---|---|---|---|---|
| 3.8 mm | 0.1496" | −0.061 mm | −0.0024" | Smaller |
| 3.9 mm | 0.1535" | +0.039 mm | +0.0015" | 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 #24 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 | 70 % | Good in steel |
Clearance for screws and bolts
Bolts and screws a #24 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" | 0.0530" | 0.0265" | – |
| #4 screw | 0.1120" | 0.0400" | 0.0200" | – |
| #5 screw | 0.1250" | 0.0270" | 0.0135" | – |
| M3.5 bolt | 3.5 mm | 0.36 mm | 0.18 mm | Close fit (close 3.7, normal 3.9 mm) |
| #6 screw | 0.1380" | 0.0140" | 0.0070" | – |
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 #24 drill?
A #24 drill is 0.1520 in, which is 3.86 mm (3.8608 mm exactly).
What is the metric equivalent of a #24 drill?
The nearest metric drill is 3.9 mm, 0.039 mm larger. The other close size is 3.8 mm.
What thread can I tap with a #24 drill?
It leaves about 70 % thread in #10-24 UNC.
Which fractional drill is closest to #24?
5/32 in (0.1562 in) is the closest, 0.0043 in larger.
What does a #24 drill clear?
It clears a #6 screw with 0.0140" total clearance (0.0070" per side).