A #59 drill measures 0.0410 inch (1.041 mm). The closest fractional drill is 3/64" (0.0469") and the closest metric drill is 1.0 mm (0.0394").
What are the #59 drill equivalents?
| Drill | System | Decimal (in) | mm | Difference (in) |
|---|---|---|---|---|
| #59 | number | 0.0410 | 1.041 | 0 |
| #61 | number | 0.0390 | 0.991 | -0.0020 |
| 1.0 mm | metric | 0.0394 | 1.000 | -0.0016 |
| #60 | number | 0.0400 | 1.016 | -0.0010 |
| #58 | number | 0.0420 | 1.067 | +0.0010 |
| #57 | number | 0.0430 | 1.092 | +0.0020 |
| 1.1 mm | metric | 0.0433 | 1.100 | +0.0023 |
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 #59 drill run?
| Material | RPM (HSS) | Feed (in/rev) |
|---|---|---|
| 6061-T6 aluminum | 18,633 | 0.0008 |
| 360 free-machining brass | 13,975 | 0.0007 |
| 1018 cold rolled steel | 7,453 | 0.0006 |
| 304 stainless steel | 3,727 | 0.0005 |
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 #59 drill in inches?
0.0410 inch, which is 1.041 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, 1.0 mm is within 0.0016 inch.
What tap uses a #59 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.