What is a 5/64" drill in decimal and mm?

0.0781 in, or 1.984 mm; nearest number / letter drill: #47 (0.0785 in, +0.0004 in); nearest metric drill: 2.0 mm (0.0787 in, +0.0006 in).

What RPM for a 5/64" drill in steel?

In low-carbon steel (1018) an HSS 5/64" drill (0.0781 in) runs about 4,400 RPM at 90 SFM; a carbide drill about 14,670 RPM at 300 SFM. RPM = 3.82 × SFM ÷ D.

What feed for a 5/64" drill?

About 0.0018 in/rev in mild steel, 0.0018 in/rev in aluminum and 0.0013 in/rev in 304 stainless. At 4,400 RPM that is 7.92 IPM in steel (IPM = RPM × IPR).

What RPM for a 5/64" drill in aluminum?

12,220 RPM with HSS (250 SFM) or up to 29,340 RPM with carbide (600 SFM), feeding about 0.0018 in/rev.

What tap uses a 5/64" drill?

2-56 (form (roll) tap, 65% thread).

5/64" drill size

A 5/64" fractional drill is 0.0781 in (1.984 mm). It is the form (roll) tap, 65% thread drill for 2-56.

Decimal inch: 0.0781
Millimeters: 1.984
Nearest 1/64: 5/64" (+0.0000)
Type: fractional drill

Nearest equivalents in other systems

Drills closest to 5/64"
System	Drill	Inch	mm	Difference
Number / letter	#47	0.0785	1.994	+0.0004 in
Metric	2.0 mm	0.0787	2.000	+0.0006 in

Speeds and feeds: in mild steel an HSS drill starts at about 4,400 RPM and 0.0018 in/rev (7.92 IPM); in 6061 aluminum about 12,220 RPM.

5/64" drill speeds and feeds by material

Jobber-length twist drill, D = 0.0781 in. RPM = 3.82 × SFM ÷ D, rounded to 10. Feed per rev scales with diameter and material; IPM = RPM × IPR.

5/64" drilling speeds
Material	HSS SFM	HSS RPM	Carbide SFM	Carbide RPM	Feed (in/rev)	HSS IPM	Carbide IPM
Aluminum (6061)	250	12,220	600	29,340	0.0018	22.0	52.8
Brass / free-machining	150	7,330	400	19,560	0.0015	11.0	29.3
Low-carbon steel (1018)	90	4,400	300	14,670	0.0018	7.92	26.4
Alloy steel (4140, annealed)	70	3,420	250	12,220	0.0018	6.16	22.0
Stainless 304	40	1,960	150	7,330	0.0013	2.55	9.53
Gray cast iron	80	3,910	250	12,220	0.0011	4.30	13.4
Titanium 6Al-4V	25	1,220	100	4,890	0.0010	1.22	4.89
Plastics (acetal)	300	14,670	500	24,450	0.0031	45.5	75.8

Small drills: the computed RPM is above most spindles. Run at your spindle's maximum and keep the feed per rev; feed drops in proportion.

Metric: Vc (m/min) = SFM × 0.3048; feed (mm/rev) = in/rev × 25.4. In steel, 4,400 RPM × 0.046 mm/rev = 201 mm/min.

Worked example: 5/64" drill in 1018 steel

HSS drill in low-carbon steel: 90 SFM.
RPM = 3.82 × 90 ÷ 0.0781 ≈ 4,400 RPM.
Feed for a 0.078 in drill in mild steel ≈ 0.0018 in/rev.
IPM = 4,400 × 0.0018 = 7.92 IPM.

Peck cycle by hole depth

5/64" drill: depth and canned cycle
Depth	Cycle	Peck	Note
3×D = 0.234 in (6 mm)	G81 (no peck)	None	Up to 3×D a sharp drill clears chips on its own.
5×D = 0.391 in (9.9 mm)	G73 chip-break	1 × D	Chip-break pecks; full retract if chips pack (soft aluminum, stainless).
8×D = 0.625 in (15.9 mm)	G83 full retract	0.5-1 × D, shrinking with depth	Retract to clear chips; reduce feed ~10-20% past 5×D.

Taps that use a 5/64" drill

2-56 — form (roll) tap, 65% thread · tap speeds and feeds

Nearest drills

#47: 0.0785 in / 1.994 mm (+0.0004 in)
2.0 mm: 0.0787 in / 2.000 mm (+0.0006 in)
1.95 mm: 0.0768 in / 1.950 mm (-0.0014 in)
#48: 0.0760 in / 1.930 mm (-0.0021 in)

Drill speed calculator, prefilled for 5/64"Drill finder: sizes near 5/64"Fractional drill chart Decimal equivalent chart

Common questions

What is a 5/64" drill in decimal and mm?: 0.0781 in, or 1.984 mm; nearest number / letter drill: #47 (0.0785 in, +0.0004 in); nearest metric drill: 2.0 mm (0.0787 in, +0.0006 in).
What RPM for a 5/64" drill in steel?: In low-carbon steel (1018) an HSS 5/64" drill (0.0781 in) runs about 4,400 RPM at 90 SFM; a carbide drill about 14,670 RPM at 300 SFM. RPM = 3.82 × SFM ÷ D.
What feed for a 5/64" drill?: About 0.0018 in/rev in mild steel, 0.0018 in/rev in aluminum and 0.0013 in/rev in 304 stainless. At 4,400 RPM that is 7.92 IPM in steel (IPM = RPM × IPR).
What RPM for a 5/64" drill in aluminum?: 12,220 RPM with HSS (250 SFM) or up to 29,340 RPM with carbide (600 SFM), feeding about 0.0018 in/rev.
What tap uses a 5/64" drill?: 2-56 (form (roll) tap, 65% thread).

Nearby drill sizes

Sources

Machinery's Handbook, 31st ed., Speeds and Feeds for Drilling, Reaming and Threading (Tables 17-23) — HSS and carbide drilling SFM (rounded).
RedLine Tools (Productivity Inc.) catalog p. 340, Cobalt & HSS Drills Speeds & Feeds — feed per rev by drill diameter and material (middle of the catalog range).
ASME B94.11M twist drills: number (#1-#80) and letter (A-Z) drill sizes; drill size reference.

Material feed multipliers (aluminum 1.3×, brass 1.1×, 4140 0.85×, stainless and titanium 0.7× the mild-steel feed) are JobLine estimates. Peck guidance is JobLine shop practice. Use your drill maker's data first.

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