What is a 9.0 mm drill in decimal and mm?

0.3543 in, or 9.000 mm; nearest fractional drill: 23/64" (0.3594 in, +0.0050 in); nearest number / letter drill: Letter T (0.3580 in, +0.0037 in).

What RPM for a 9.0 mm drill in steel?

In low-carbon steel (1018) an HSS 9.0 mm drill (0.3543 in) runs about 970 RPM at 90 SFM; a carbide drill about 3,230 RPM at 300 SFM. RPM = 3.82 × SFM ÷ D.

What feed for a 9.0 mm drill?

About 0.0090 in/rev in mild steel, 0.0081 in/rev in aluminum and 0.0059 in/rev in 304 stainless. At 970 RPM that is 8.73 IPM in steel (IPM = RPM × IPR).

What RPM for a 9.0 mm drill in aluminum?

2,700 RPM with HSS (250 SFM) or up to 6,470 RPM with carbide (600 SFM), feeding about 0.0081 in/rev.

What tap uses a 9.0 mm drill?

M10x1 (cut tap, 75% thread); M10×1.5 (cut tap, 50% thread); M8×1.25 (Helicoil / STI insert (M8×1.25×1D)).

9.0 mm drill size

A 9.0 mm metric drill is 0.3543 in (9.000 mm). It is the cut tap, 75% thread drill for M10x1.

Decimal inch: 0.3543
Millimeters: 9.000
Nearest 1/64: 23/64" (-0.0050)
Type: metric drill

Nearest equivalents in other systems

Drills closest to 9.0 mm
System	Drill	Inch	mm	Difference
Fractional	23/64"	0.3594	9.128	+0.0050 in
Number / letter	Letter T	0.3580	9.093	+0.0037 in

Speeds and feeds: in mild steel an HSS drill starts at about 970 RPM and 0.0090 in/rev (8.73 IPM); in 6061 aluminum about 2,700 RPM.

9.0 mm drill speeds and feeds by material

Jobber-length twist drill, D = 0.3543 in. RPM = 3.82 × SFM ÷ D, rounded to 10. Feed per rev scales with diameter and material; IPM = RPM × IPR.

9.0 mm drilling speeds
Material	HSS SFM	HSS RPM	Carbide SFM	Carbide RPM	Feed (in/rev)	HSS IPM	Carbide IPM
Aluminum (6061)	250	2,700	600	6,470	0.0081	21.9	52.4
Brass / free-machining	150	1,620	400	4,310	0.0061	9.88	26.3
Low-carbon steel (1018)	90	970	300	3,230	0.0090	8.73	29.1
Alloy steel (4140, annealed)	70	750	250	2,700	0.0098	7.35	26.5
Stainless 304	40	430	150	1,620	0.0059	2.54	9.56
Gray cast iron	80	860	250	2,700	0.0062	5.33	16.7
Titanium 6Al-4V	25	270	100	1,080	0.0040	1.08	4.32
Plastics (acetal)	300	3,230	500	5,390	0.0048	15.5	25.9

Metric: Vc (m/min) = SFM × 0.3048; feed (mm/rev) = in/rev × 25.4. In steel, 970 RPM × 0.229 mm/rev = 222 mm/min.

Worked example: 9.0 mm drill in 1018 steel

HSS drill in low-carbon steel: 90 SFM.
RPM = 3.82 × 90 ÷ 0.3543 ≈ 970 RPM.
Feed for a 0.354 in drill in mild steel ≈ 0.0090 in/rev.
IPM = 970 × 0.0090 = 8.73 IPM.

Peck cycle by hole depth

9.0 mm drill: depth and canned cycle
Depth	Cycle	Peck	Note
3×D = 1.063 in (27 mm)	G81 (no peck)	None	Up to 3×D a sharp drill clears chips on its own.
5×D = 1.772 in (45 mm)	G73 chip-break	1 × D	Chip-break pecks; full retract if chips pack (soft aluminum, stainless).
8×D = 2.835 in (72 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 9.0 mm drill

M10x1 — cut tap, 75% thread
M10×1.5 — cut tap, 50% thread · tap speeds and feeds
M8×1.25 — Helicoil / STI insert (M8×1.25×1D) · tap speeds and feeds

Nearest drills

Letter T: 0.3580 in / 9.093 mm (+0.0037 in)
8.9 mm: 0.3504 in / 8.900 mm (-0.0039 in)
9.1 mm: 0.3583 in / 9.100 mm (+0.0039 in)
23/64": 0.3594 in / 9.128 mm (+0.0050 in)

Drill speed calculator, prefilled for 9.0 mm Drill finder: sizes near 9.0 mm Metric drill chart Decimal equivalent chart

Common questions

What is a 9.0 mm drill in decimal and mm?: 0.3543 in, or 9.000 mm; nearest fractional drill: 23/64" (0.3594 in, +0.0050 in); nearest number / letter drill: Letter T (0.3580 in, +0.0037 in).
What RPM for a 9.0 mm drill in steel?: In low-carbon steel (1018) an HSS 9.0 mm drill (0.3543 in) runs about 970 RPM at 90 SFM; a carbide drill about 3,230 RPM at 300 SFM. RPM = 3.82 × SFM ÷ D.
What feed for a 9.0 mm drill?: About 0.0090 in/rev in mild steel, 0.0081 in/rev in aluminum and 0.0059 in/rev in 304 stainless. At 970 RPM that is 8.73 IPM in steel (IPM = RPM × IPR).
What RPM for a 9.0 mm drill in aluminum?: 2,700 RPM with HSS (250 SFM) or up to 6,470 RPM with carbide (600 SFM), feeding about 0.0081 in/rev.
What tap uses a 9.0 mm drill?: M10x1 (cut tap, 75% thread); M10×1.5 (cut tap, 50% thread); M8×1.25 (Helicoil / STI insert (M8×1.25×1D)).

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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