What is a #22 drill in decimal and mm?

0.1570 in, or 3.988 mm; nearest fractional drill: 5/32" (0.1563 in, -0.0008 in); nearest metric drill: 4.0 mm (0.1575 in, +0.0005 in).

What RPM for a #22 drill in steel?

In low-carbon steel (1018) an HSS #22 drill (0.1570 in) runs about 2,190 RPM at 90 SFM; a carbide drill about 7,300 RPM at 300 SFM. RPM = 3.82 × SFM ÷ D.

What feed for a #22 drill?

About 0.0039 in/rev in mild steel, 0.0037 in/rev in aluminum and 0.0026 in/rev in 304 stainless. At 2,190 RPM that is 8.54 IPM in steel (IPM = RPM × IPR).

What RPM for a #22 drill in aluminum?

6,080 RPM with HSS (250 SFM) or up to 14,600 RPM with carbide (600 SFM), feeding about 0.0037 in/rev.

What size is a #22 drill?

0.1570 in / 3.988 mm. The nearest other drills are 4.0 mm (0.1575 in), 5/32" (0.1563 in), #21 (0.1590 in).

#22 drill size

A #22 number (wire-gauge) drill is 0.1570 in (3.988 mm).

Decimal inch: 0.1570
Millimeters: 3.988
Nearest 1/64: 5/32" (+0.0008)
Type: number (wire-gauge) drill

Nearest equivalents in other systems

Drills closest to #22
System	Drill	Inch	mm	Difference
Fractional	5/32"	0.1563	3.969	-0.0008 in
Metric	4.0 mm	0.1575	4.000	+0.0005 in

Speeds and feeds: in mild steel an HSS drill starts at about 2,190 RPM and 0.0039 in/rev (8.54 IPM); in 6061 aluminum about 6,080 RPM.

#22 drill speeds and feeds by material

Jobber-length twist drill, D = 0.1570 in. RPM = 3.82 × SFM ÷ D, rounded to 10. Feed per rev scales with diameter and material; IPM = RPM × IPR.

#22 drilling speeds
Material	HSS SFM	HSS RPM	Carbide SFM	Carbide RPM	Feed (in/rev)	HSS IPM	Carbide IPM
Aluminum (6061)	250	6,080	600	14,600	0.0037	22.5	54.0
Brass / free-machining	150	3,650	400	9,730	0.0031	11.3	30.2
Low-carbon steel (1018)	90	2,190	300	7,300	0.0039	8.54	28.5
Alloy steel (4140, annealed)	70	1,700	250	6,080	0.0039	6.63	23.7
Stainless 304	40	970	150	3,650	0.0026	2.52	9.49
Gray cast iron	80	1,950	250	6,080	0.0025	4.88	15.2
Titanium 6Al-4V	25	610	100	2,430	0.0019	1.16	4.62
Plastics (acetal)	300	7,300	500	12,160	0.0047	34.3	57.1

Metric: Vc (m/min) = SFM × 0.3048; feed (mm/rev) = in/rev × 25.4. In steel, 2,190 RPM × 0.099 mm/rev = 217 mm/min.

Worked example: #22 drill in 1018 steel

HSS drill in low-carbon steel: 90 SFM.
RPM = 3.82 × 90 ÷ 0.1570 ≈ 2,190 RPM.
Feed for a 0.157 in drill in mild steel ≈ 0.0039 in/rev.
IPM = 2,190 × 0.0039 = 8.54 IPM.

Peck cycle by hole depth

#22 drill: depth and canned cycle
Depth	Cycle	Peck	Note
3×D = 0.471 in (12 mm)	G81 (no peck)	None	Up to 3×D a sharp drill clears chips on its own.
5×D = 0.785 in (19.9 mm)	G73 chip-break	1 × D	Chip-break pecks; full retract if chips pack (soft aluminum, stainless).
8×D = 1.256 in (31.9 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 #22 drill

No standard UNC, UNF or metric tap in our tables calls for a #22 drill. Use it for clearance, pilot or reamer prep holes.

Nearest drills

4.0 mm: 0.1575 in / 4.000 mm (+0.0005 in)
5/32": 0.1563 in / 3.969 mm (-0.0008 in)
#21: 0.1590 in / 4.039 mm (+0.0020 in)
#23: 0.1540 in / 3.912 mm (-0.0030 in)

Drill speed calculator, prefilled for #22 Drill finder: sizes near #22 Number drill chart Decimal equivalent chart

Common questions

What is a #22 drill in decimal and mm?: 0.1570 in, or 3.988 mm; nearest fractional drill: 5/32" (0.1563 in, -0.0008 in); nearest metric drill: 4.0 mm (0.1575 in, +0.0005 in).
What RPM for a #22 drill in steel?: In low-carbon steel (1018) an HSS #22 drill (0.1570 in) runs about 2,190 RPM at 90 SFM; a carbide drill about 7,300 RPM at 300 SFM. RPM = 3.82 × SFM ÷ D.
What feed for a #22 drill?: About 0.0039 in/rev in mild steel, 0.0037 in/rev in aluminum and 0.0026 in/rev in 304 stainless. At 2,190 RPM that is 8.54 IPM in steel (IPM = RPM × IPR).
What RPM for a #22 drill in aluminum?: 6,080 RPM with HSS (250 SFM) or up to 14,600 RPM with carbide (600 SFM), feeding about 0.0037 in/rev.
What size is a #22 drill?: 0.1570 in / 3.988 mm. The nearest other drills are 4.0 mm (0.1575 in), 5/32" (0.1563 in), #21 (0.1590 in).

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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