#7 drill size
A #7 drill is 0.2010 in (5.11 mm). It is the standard tap drill for 1/4-20 UNC; the nearest metric drill is 5.1 mm.
#7 at a glance
Decimal, metric and the nearest sizes in the other series.
- Decimal inch
- 0.2010"
- Millimetres
- 5.11 mm 5.1054
- Nearest metric drill
- 5.1 mm −0.005 mm
- Nearest fractional
- 13/64" 0.2031", +0.0021"
- Hole area
- 0.0317 in² 20.47 mm²
- Tap drill for
- 1/4-20 UNC
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 |
|---|---|---|---|---|
| 5.1 mm | 0.2008" | −0.005 mm | −0.0002" | Smaller |
| 5.2 mm | 0.2047" | +0.095 mm | +0.0037" | 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 #7 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 |
|---|---|---|---|
| 1/4-20 UNC | #7 | 75 % | Standard drill |
| M6 × 1 | 5 mm | 69 % | Good in steel |
Clearance for screws and bolts
Bolts and screws a #7 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" | 0.0370" | 0.0185" | – |
| #10 screw | 0.1900" | 0.0110" | 0.0055" | – |
| M5 bolt | 5 mm | 0.11 mm | 0.05 mm | Tighter than close fit (5.3 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 #7 drill?
A #7 drill is 0.2010 in, which is 5.11 mm (5.1054 mm exactly).
What is the metric equivalent of a #7 drill?
The nearest metric drill is 5.1 mm, 0.005 mm smaller. The other close size is 5.2 mm.
What tap uses a #7 drill?
A #7 drill is the standard tap drill for 1/4-20 UNC (about 75 % thread).
Which fractional drill is closest to #7?
13/64 in (0.2031 in) is the closest, 0.0021 in larger.
What does a #7 drill clear?
It clears a M5 bolt with 0.11 mm total clearance (0.05 mm per side); for metric bolts: tighter than close fit.