Letter V drill size
A letter V drill is 0.3770 in (9.58 mm). It sits between letter U and letter W in the letter series; the nearest metric drill is 9.6 mm.
Letter V 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 |
|---|---|---|---|---|
| 9.5 mm | 0.3740" | −0.076 mm | −0.0030" | Smaller |
| 9.6 mm | 0.3780" | +0.024 mm | +0.0010" | Larger |
Nearby inch drills
The next size down and up in each inch series, so you can pick a substitute from the drawer.
| Drill | Series | Inch | mm | Difference |
|---|---|---|---|---|
| #1 | Number | 0.2280" | 5.79 mm | −0.1490" |
| Letter U | Letter | 0.3680" | 9.35 mm | −0.0090" |
| 3/8" | Fractional | 0.3750" | 9.52 mm | −0.0020" |
| Letter V | Letter | 0.3770" | 9.58 mm | this size |
| Letter W | Letter | 0.3860" | 9.80 mm | +0.0090" |
| 25/64" | Fractional | 0.3906" | 9.92 mm | +0.0136" |
Threads a Letter V 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 |
|---|---|---|---|
| 7/16-14 UNC | U | 65 % | Good in steel |
Clearance for screws and bolts
Bolts and screws a Letter V 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 |
|---|---|---|---|---|
| M8 bolt | 8 mm | 1.58 mm | 0.79 mm | Normal fit (normal 9, loose 10 mm) |
| 3/8" bolt | 0.3750" | 0.0020" | 0.0010" | – |
Inch clearance is the drill size minus the basic major diameter. A drilled hole usually cuts slightly oversize.
Letter drill index
Every size in the series, holes drawn to scale.
Common questions
What size is a letter V drill?
A letter V drill is 0.3770 in, which is 9.58 mm (9.5758 mm exactly).
What is the metric equivalent of a letter V drill?
The nearest metric drill is 9.6 mm, 0.024 mm larger. The other close size is 9.5 mm.
What thread can I tap with a letter V drill?
It leaves about 65 % thread in 7/16-14 UNC.
Which fractional drill is closest to letter V?
3/8 in (0.3750 in) is the closest, 0.0020 in smaller.
What does a letter V drill clear?
It clears a 3/8" bolt with 0.0020" total clearance (0.0010" per side).