What is a #47 drill in decimal and mm?

0.0785 in, or 1.994 mm; nearest fractional drill: 5/64" (0.0781 in, -0.0004 in); nearest metric drill: 2.0 mm (0.0787 in, +0.0002 in).

What RPM for a #47 drill in steel?

In low-carbon steel (1018) an HSS #47 drill (0.0785 in) runs about 4,380 RPM at 90 SFM; a carbide drill about 14,600 RPM at 300 SFM. RPM = 3.82 × SFM ÷ D.

What feed for a #47 drill?

About 0.0019 in/rev in mild steel, 0.0018 in/rev in aluminum and 0.0013 in/rev in 304 stainless. At 4,380 RPM that is 8.32 IPM in steel (IPM = RPM × IPR).

What RPM for a #47 drill in aluminum?

12,160 RPM with HSS (250 SFM) or up to 29,200 RPM with carbide (600 SFM), feeding about 0.0018 in/rev.

What tap uses a #47 drill?

3-48 (cut tap, 75% thread); 2-64 (form (roll) tap, 65% thread).

#47 drill size

A #47 number (wire-gauge) drill is 0.0785 in (1.994 mm). It is the cut tap, 75% thread drill for 3-48.

Decimal inch: 0.0785
Millimeters: 1.994
Nearest 1/64: 5/64" (+0.0004)
Type: number (wire-gauge) drill

Nearest equivalents in other systems

Drills closest to #47
System	Drill	Inch	mm	Difference
Fractional	5/64"	0.0781	1.984	-0.0004 in
Metric	2.0 mm	0.0787	2.000	+0.0002 in

Speeds and feeds: in mild steel an HSS drill starts at about 4,380 RPM and 0.0019 in/rev (8.32 IPM); in 6061 aluminum about 12,160 RPM.

#47 drill speeds and feeds by material

Jobber-length twist drill, D = 0.0785 in. RPM = 3.82 × SFM ÷ D, rounded to 10. Feed per rev scales with diameter and material; IPM = RPM × IPR.

#47 drilling speeds
Material	HSS SFM	HSS RPM	Carbide SFM	Carbide RPM	Feed (in/rev)	HSS IPM	Carbide IPM
Aluminum (6061)	250	12,160	600	29,200	0.0018	21.9	52.6
Brass / free-machining	150	7,300	400	19,460	0.0015	10.9	29.2
Low-carbon steel (1018)	90	4,380	300	14,600	0.0019	8.32	27.7
Alloy steel (4140, annealed)	70	3,410	250	12,160	0.0019	6.48	23.1
Stainless 304	40	1,950	150	7,300	0.0013	2.53	9.49
Gray cast iron	80	3,890	250	12,160	0.0011	4.28	13.4
Titanium 6Al-4V	25	1,220	100	4,870	0.0010	1.22	4.87
Plastics (acetal)	300	14,600	500	24,330	0.0031	45.3	75.4

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, 4,380 RPM × 0.048 mm/rev = 211 mm/min.

Worked example: #47 drill in 1018 steel

HSS drill in low-carbon steel: 90 SFM.
RPM = 3.82 × 90 ÷ 0.0785 ≈ 4,380 RPM.
Feed for a 0.079 in drill in mild steel ≈ 0.0019 in/rev.
IPM = 4,380 × 0.0019 = 8.32 IPM.

Peck cycle by hole depth

#47 drill: depth and canned cycle
Depth	Cycle	Peck	Note
3×D = 0.236 in (6 mm)	G81 (no peck)	None	Up to 3×D a sharp drill clears chips on its own.
5×D = 0.393 in (10 mm)	G73 chip-break	1 × D	Chip-break pecks; full retract if chips pack (soft aluminum, stainless).
8×D = 0.628 in (16 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 #47 drill

3-48 — cut tap, 75% thread · tap speeds and feeds
2-64 — form (roll) tap, 65% thread · tap speeds and feeds

Nearest drills

2.0 mm: 0.0787 in / 2.000 mm (+0.0002 in)
5/64": 0.0781 in / 1.984 mm (-0.0004 in)
1.95 mm: 0.0768 in / 1.950 mm (-0.0017 in)
2.05 mm: 0.0807 in / 2.050 mm (+0.0022 in)

Drill speed calculator, prefilled for #47 Drill finder: sizes near #47 Number drill chart Decimal equivalent chart

Common questions

What is a #47 drill in decimal and mm?: 0.0785 in, or 1.994 mm; nearest fractional drill: 5/64" (0.0781 in, -0.0004 in); nearest metric drill: 2.0 mm (0.0787 in, +0.0002 in).
What RPM for a #47 drill in steel?: In low-carbon steel (1018) an HSS #47 drill (0.0785 in) runs about 4,380 RPM at 90 SFM; a carbide drill about 14,600 RPM at 300 SFM. RPM = 3.82 × SFM ÷ D.
What feed for a #47 drill?: About 0.0019 in/rev in mild steel, 0.0018 in/rev in aluminum and 0.0013 in/rev in 304 stainless. At 4,380 RPM that is 8.32 IPM in steel (IPM = RPM × IPR).
What RPM for a #47 drill in aluminum?: 12,160 RPM with HSS (250 SFM) or up to 29,200 RPM with carbide (600 SFM), feeding about 0.0018 in/rev.
What tap uses a #47 drill?: 3-48 (cut tap, 75% thread); 2-64 (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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