What is a 10.2 mm drill in decimal and mm?

0.4016 in, or 10.200 mm; nearest fractional drill: 13/32" (0.4063 in, +0.0047 in); nearest number / letter drill: Letter Y (0.4040 in, +0.0024 in).

What RPM for a 10.2 mm drill in steel?

In low-carbon steel (1018) an HSS 10.2 mm drill (0.4016 in) runs about 860 RPM at 90 SFM; a carbide drill about 2,850 RPM at 300 SFM. RPM = 3.82 × SFM ÷ D.

What feed for a 10.2 mm drill?

About 0.0097 in/rev in mild steel, 0.0088 in/rev in aluminum and 0.0067 in/rev in 304 stainless. At 860 RPM that is 8.34 IPM in steel (IPM = RPM × IPR).

What RPM for a 10.2 mm drill in aluminum?

2,380 RPM with HSS (250 SFM) or up to 5,710 RPM with carbide (600 SFM), feeding about 0.0088 in/rev.

What tap uses a 10.2 mm drill?

M12×1.75 (cut tap, 75% thread).

10.2 mm drill size

A 10.2 mm metric drill is 0.4016 in (10.200 mm). It is the cut tap, 75% thread drill for M12×1.75.

Decimal inch: 0.4016
Millimeters: 10.200
Nearest 1/64: 13/32" (-0.0047)
Type: metric drill

Nearest equivalents in other systems

Drills closest to 10.2 mm
System	Drill	Inch	mm	Difference
Fractional	13/32"	0.4063	10.319	+0.0047 in
Number / letter	Letter Y	0.4040	10.262	+0.0024 in

Speeds and feeds: in mild steel an HSS drill starts at about 860 RPM and 0.0097 in/rev (8.34 IPM); in 6061 aluminum about 2,380 RPM.

10.2 mm drill speeds and feeds by material

Jobber-length twist drill, D = 0.4016 in. RPM = 3.82 × SFM ÷ D, rounded to 10. Feed per rev scales with diameter and material; IPM = RPM × IPR.

10.2 mm drilling speeds
Material	HSS SFM	HSS RPM	Carbide SFM	Carbide RPM	Feed (in/rev)	HSS IPM	Carbide IPM
Aluminum (6061)	250	2,380	600	5,710	0.0088	20.9	50.3
Brass / free-machining	150	1,430	400	3,800	0.0067	9.58	25.5
Low-carbon steel (1018)	90	860	300	2,850	0.0097	8.34	27.6
Alloy steel (4140, annealed)	70	670	250	2,380	0.0107	7.17	25.5
Stainless 304	40	380	150	1,430	0.0067	2.55	9.58
Gray cast iron	80	760	250	2,380	0.0069	5.24	16.4
Titanium 6Al-4V	25	240	100	950	0.0044	1.06	4.18
Plastics (acetal)	300	2,850	500	4,760	0.0052	14.8	24.8

Metric: Vc (m/min) = SFM × 0.3048; feed (mm/rev) = in/rev × 25.4. In steel, 860 RPM × 0.246 mm/rev = 212 mm/min.

Worked example: 10.2 mm drill in 1018 steel

HSS drill in low-carbon steel: 90 SFM.
RPM = 3.82 × 90 ÷ 0.4016 ≈ 860 RPM.
Feed for a 0.402 in drill in mild steel ≈ 0.0097 in/rev.
IPM = 860 × 0.0097 = 8.34 IPM.

Peck cycle by hole depth

10.2 mm drill: depth and canned cycle
Depth	Cycle	Peck	Note
3×D = 1.205 in (30.6 mm)	G81 (no peck)	None	Up to 3×D a sharp drill clears chips on its own.
5×D = 2.008 in (51 mm)	G73 chip-break	1 × D	Chip-break pecks; full retract if chips pack (soft aluminum, stainless).
8×D = 3.213 in (81.6 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 10.2 mm drill

M12×1.75 — cut tap, 75% thread · tap speeds and feeds

Nearest drills

Letter Y: 0.4040 in / 10.262 mm (+0.0024 in)
10.1 mm: 0.3976 in / 10.100 mm (-0.0039 in)
10.3 mm: 0.4055 in / 10.300 mm (+0.0039 in)
Letter X: 0.3970 in / 10.084 mm (-0.0046 in)

Drill speed calculator, prefilled for 10.2 mm Drill finder: sizes near 10.2 mm Metric drill chart Decimal equivalent chart

Common questions

What is a 10.2 mm drill in decimal and mm?: 0.4016 in, or 10.200 mm; nearest fractional drill: 13/32" (0.4063 in, +0.0047 in); nearest number / letter drill: Letter Y (0.4040 in, +0.0024 in).
What RPM for a 10.2 mm drill in steel?: In low-carbon steel (1018) an HSS 10.2 mm drill (0.4016 in) runs about 860 RPM at 90 SFM; a carbide drill about 2,850 RPM at 300 SFM. RPM = 3.82 × SFM ÷ D.
What feed for a 10.2 mm drill?: About 0.0097 in/rev in mild steel, 0.0088 in/rev in aluminum and 0.0067 in/rev in 304 stainless. At 860 RPM that is 8.34 IPM in steel (IPM = RPM × IPR).
What RPM for a 10.2 mm drill in aluminum?: 2,380 RPM with HSS (250 SFM) or up to 5,710 RPM with carbide (600 SFM), feeding about 0.0088 in/rev.
What tap uses a 10.2 mm drill?: M12×1.75 (cut tap, 75% 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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