A #6 drill measures 0.2040 inch (5.182 mm). The closest fractional drill is 13/64" (0.2031") and the closest metric drill is 5.2 mm (0.2047").
What are the #6 drill equivalents?
| Drill | System | Decimal (in) | mm | Difference (in) |
|---|---|---|---|---|
| #6 | number | 0.2040 | 5.182 | 0 |
| #7 | number | 0.2010 | 5.105 | -0.0030 |
| 13/64" | fraction | 0.2031 | 5.159 | -0.0009 |
| 5.2 mm | metric | 0.2047 | 5.200 | +0.0007 |
| #5 | number | 0.2055 | 5.220 | +0.0015 |
Drill sets that include this size
Number and letter sizes come in indexed sets; buy the set rather than single drills.
What speed should a #6 drill run?
| Material | RPM (HSS) | Feed (in/rev) |
|---|---|---|
| 6061-T6 aluminum | 3,745 | 0.0041 |
| 360 free-machining brass | 2,809 | 0.0037 |
| 1018 cold rolled steel | 1,498 | 0.0031 |
| 304 stainless steel | 749 | 0.0020 |
Starting points from conservative HSS drilling speeds. Small drills often call for more RPM than a benchtop drill press offers; run at the top speed and feed gently. Use cutting oil in steel and stainless, and clamp the work: never hold it by hand.
Cutting fluid for drilling
Frequently asked questions
What is a #6 drill in inches?
0.2040 inch, which is 5.182 mm. Number drills get smaller as the number rises, so the next number up is a smaller drill. If you do not have this exact size, 5.2 mm is within 0.0007 inch.
What tap uses a #6 drill?
No common UNC or UNF thread uses it as its standard 75% tap drill, but it often serves as an alternative drill for a slightly different percentage of thread, or as a clearance or pilot size. The tap drill chart lists every standard pairing.