What is a 25/32" drill in decimal and mm?

0.7813 in, or 19.844 mm; nearest number / letter drill: Letter Z (0.4130 in, -0.3683 in); nearest metric drill: 19.75 mm (0.7776 in, -0.0037 in).

What RPM for a 25/32" drill in steel?

In low-carbon steel (1018) an HSS 25/32" drill (0.7813 in) runs about 440 RPM at 90 SFM; a carbide drill about 1,470 RPM at 300 SFM. RPM = 3.82 × SFM ÷ D.

What feed for a 25/32" drill?

About 0.0116 in/rev in mild steel, 0.0113 in/rev in aluminum and 0.0096 in/rev in 304 stainless. At 440 RPM that is 5.10 IPM in steel (IPM = RPM × IPR).

What RPM for a 25/32" drill in aluminum?

1,220 RPM with HSS (250 SFM) or up to 2,930 RPM with carbide (600 SFM), feeding about 0.0113 in/rev.

What tap uses a 25/32" drill?

13/16-20 (cut tap, 50% thread).

25/32" drill size

A 25/32" fractional drill is 0.7813 in (19.844 mm). It is the cut tap, 50% thread drill for 13/16-20.

Decimal inch: 0.7813
Millimeters: 19.844
Nearest 1/64: 25/32" (+0.0000)
Type: fractional drill

Nearest equivalents in other systems

Drills closest to 25/32"
System	Drill	Inch	mm	Difference
Number / letter	Letter Z	0.4130	10.490	-0.3683 in
Metric	19.75 mm	0.7776	19.750	-0.0037 in

Speeds and feeds: in mild steel an HSS drill starts at about 440 RPM and 0.0116 in/rev (5.10 IPM); in 6061 aluminum about 1,220 RPM.

25/32" drill speeds and feeds by material

Jobber-length twist drill, D = 0.7813 in. RPM = 3.82 × SFM ÷ D, rounded to 10. Feed per rev scales with diameter and material; IPM = RPM × IPR.

25/32" drilling speeds
Material	HSS SFM	HSS RPM	Carbide SFM	Carbide RPM	Feed (in/rev)	HSS IPM	Carbide IPM
Aluminum (6061)	250	1,220	600	2,930	0.0113	13.8	33.1
Brass / free-machining	150	730	400	1,960	0.0091	6.64	17.8
Low-carbon steel (1018)	90	440	300	1,470	0.0116	5.10	17.1
Alloy steel (4140, annealed)	70	340	250	1,220	0.0121	4.11	14.8
Stainless 304	40	200	150	730	0.0096	1.92	7.01
Gray cast iron	80	390	250	1,220	0.0101	3.94	12.3
Titanium 6Al-4V	25	120	100	490	0.0056	0.67	2.74
Plastics (acetal)	300	1,470	500	2,440	0.0071	10.4	17.3

Metric: Vc (m/min) = SFM × 0.3048; feed (mm/rev) = in/rev × 25.4. In steel, 440 RPM × 0.295 mm/rev = 130 mm/min.

Worked example: 25/32" drill in 1018 steel

HSS drill in low-carbon steel: 90 SFM.
RPM = 3.82 × 90 ÷ 0.7813 ≈ 440 RPM.
Feed for a 0.781 in drill in mild steel ≈ 0.0116 in/rev.
IPM = 440 × 0.0116 = 5.10 IPM.

Peck cycle by hole depth

25/32" drill: depth and canned cycle
Depth	Cycle	Peck	Note
3×D = 2.344 in (59.5 mm)	G81 (no peck)	None	Up to 3×D a sharp drill clears chips on its own.
5×D = 3.906 in (99.2 mm)	G73 chip-break	1 × D	Chip-break pecks; full retract if chips pack (soft aluminum, stainless).
8×D = 6.250 in (158.8 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 25/32" drill

13/16-20 — cut tap, 50% thread

Nearest drills

19.75 mm: 0.7776 in / 19.750 mm (-0.0037 in)
20.0 mm: 0.7874 in / 20.000 mm (+0.0062 in)
19.5 mm: 0.7677 in / 19.500 mm (-0.0135 in)
49/64": 0.7656 in / 19.447 mm (-0.0156 in)

Drill speed calculator, prefilled for 25/32"Drill finder: sizes near 25/32"Fractional drill chart Decimal equivalent chart

Common questions

What is a 25/32" drill in decimal and mm?: 0.7813 in, or 19.844 mm; nearest number / letter drill: Letter Z (0.4130 in, -0.3683 in); nearest metric drill: 19.75 mm (0.7776 in, -0.0037 in).
What RPM for a 25/32" drill in steel?: In low-carbon steel (1018) an HSS 25/32" drill (0.7813 in) runs about 440 RPM at 90 SFM; a carbide drill about 1,470 RPM at 300 SFM. RPM = 3.82 × SFM ÷ D.
What feed for a 25/32" drill?: About 0.0116 in/rev in mild steel, 0.0113 in/rev in aluminum and 0.0096 in/rev in 304 stainless. At 440 RPM that is 5.10 IPM in steel (IPM = RPM × IPR).
What RPM for a 25/32" drill in aluminum?: 1,220 RPM with HSS (250 SFM) or up to 2,930 RPM with carbide (600 SFM), feeding about 0.0113 in/rev.
What tap uses a 25/32" drill?: 13/16-20 (cut tap, 50% 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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