#4 drill size
A #4 drill is 0.2090 in (5.31 mm). It sits between #5 and #3 in the number series; the nearest metric drill is 5.3 mm.
#4 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 |
|---|---|---|---|---|
| 5.3 mm | 0.2087" | −0.009 mm | −0.0003" | Smaller |
| 5.4 mm | 0.2126" | +0.091 mm | +0.0036" | 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 #4 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 |
|---|---|---|---|
| M6 × 0.75 | 5.2 mm | 71 % | Good in steel |
| 1/4-20 UNC | #7 | 63 % | Hard, tough metals |
Clearance for screws and bolts
Bolts and screws a #4 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 |
|---|---|---|---|---|
| #8 screw | 0.1640" | 0.0450" | 0.0225" | – |
| #10 screw | 0.1900" | 0.0190" | 0.0095" | – |
| M5 bolt | 5 mm | 0.31 mm | 0.15 mm | Close fit (close 5.3, normal 5.5 mm) |
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 #4 drill?
A #4 drill is 0.2090 in, which is 5.31 mm (5.3086 mm exactly).
What is the metric equivalent of a #4 drill?
The nearest metric drill is 5.3 mm, 0.009 mm smaller. The other close size is 5.4 mm.
What thread can I tap with a #4 drill?
It leaves about 71 % thread in M6 × 0.75 and 63 % in 1/4-20 UNC.
Which fractional drill is closest to #4?
13/64 in (0.2031 in) is the closest, 0.0059 in smaller.
What does a #4 drill clear?
It clears a M5 bolt with 0.31 mm total clearance (0.15 mm per side); for metric bolts: close fit.