A #10 drill measures 0.1935 inch (4.915 mm). The closest fractional drill is 3/16" (0.1875") and the closest metric drill is 4.9 mm (0.1929").
What are the #10 drill equivalents?
| Drill | System | Decimal (in) | mm | Difference (in) |
|---|---|---|---|---|
| #10 | number | 0.1935 | 4.915 | 0 |
| #11 | number | 0.1910 | 4.851 | -0.0025 |
| 4.9 mm | metric | 0.1929 | 4.900 | -0.0006 |
| #9 | number | 0.1960 | 4.978 | +0.0025 |
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 #10 drill run?
| Material | RPM (HSS) | Feed (in/rev) |
|---|---|---|
| 6061-T6 aluminum | 3,948 | 0.0039 |
| 360 free-machining brass | 2,961 | 0.0035 |
| 1018 cold rolled steel | 1,579 | 0.0029 |
| 304 stainless steel | 790 | 0.0019 |
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 #10 drill in inches?
0.1935 inch, which is 4.915 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, 4.9 mm is within 0.0006 inch.
What tap uses a #10 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.