End Mill Size Chart: 1/32" to 1" Dimensions

Q: How many flutes should my end mill have?

Use 2 flutes for aluminum and soft metals. The wider flute valleys clear chips fast. Use 3 or 4 flutes for steel and harder materials. More flutes give a smoother finish but leave less room for chips.

Q: What is flute length vs. overall length?

Flute length is the cutting portion of the tool. Overall length includes the shank. Use a flute length at least as long as your cut depth. Shorter flute lengths reduce deflection and chatter.

Q: Should I use a fractional or metric end mill?

Match the end mill to your drawing units. If the part is dimensioned in inches, use fractional sizes. If it is in millimeters, use metric. Mixing systems can cause tolerance errors on slot widths and pocket sizes.

Diameter (in) ▲	Diameter (mm) ▲	Flutes ▲	Shank Dia (in) ▲	Overall Length (in) ▲	Flute Length (in) ▲	Recommended Material ▲
1/32"	0.79	2	1/8"	1-1/2"	3/32"	Aluminum, plastics, soft metals
1/16"	1.59	2	1/8"	1-1/2"	1/4"	Aluminum, brass, acetal
3/32"	2.38	2	1/8"	1-1/2"	3/8"	Aluminum, copper, plastics
1/8"	3.18	2	1/8"	1-1/2"	1/2"	Aluminum, brass, mild steel
5/32"	3.97	4	3/16"	2"	9/16"	Steel, stainless, titanium
3/16"	4.76	4	3/16"	2"	5/8"	Steel, stainless steel
1/4"	6.35	2	1/4"	2-1/2"	3/4"	Aluminum, brass, plastics
1/4"	6.35	4	1/4"	2-1/2"	3/4"	Steel, stainless, cast iron
5/16"	7.94	4	5/16"	2-1/2"	13/16"	Steel, stainless steel
3/8"	9.53	2	3/8"	2-1/2"	7/8"	Aluminum, copper alloys
3/8"	9.53	4	3/8"	2-1/2"	7/8"	Steel, tool steel, titanium
1/2"	12.70	2	1/2"	3"	1"	Aluminum, brass, acetal
1/2"	12.70	4	1/2"	3"	1"	Steel, stainless, Inconel
5/8"	15.88	4	5/8"	3-1/2"	1-1/4"	Steel, cast iron, stainless
3/4"	19.05	4	3/4"	4"	1-1/2"	Steel, tool steel, cast iron
1"	25.40	4	1"	4"	1-1/2"	Steel, stainless, Inconel
0.039" (1mm)	1.00	2	1/8"	1-1/2"	3/16"	Aluminum, plastics
0.079" (2mm)	2.00	2	1/8"	1-1/2"	1/4"	Aluminum, brass, acetal
0.118" (3mm)	3.00	2	1/8"	1-1/2"	3/8"	Aluminum, mild steel
0.197" (5mm)	5.00	4	6mm	2"	5/8"	Steel, stainless steel
0.315" (8mm)	8.00	4	8mm	2-1/2"	7/8"	Steel, titanium, Inconel
0.394" (10mm)	10.00	4	10mm	3"	1"	Steel, stainless, tool steel

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Notes on This Chart

Use 2-flute end mills for aluminum and soft metals. Use 4-flute for steel and harder alloys.
Shank diameter must match your collet or tool holder size.
Flute lengths shown are standard. Long-reach and stub options are also available.
Material recommendations are general. Always check your tooling catalog for coatings and grades.

Frequently Asked Questions

How many flutes should my end mill have?

Use 2 flutes for aluminum and soft metals. The wide flute valleys clear chips fast. Use 3 or 4 flutes for steel and harder materials. More flutes give a smoother finish but leave less room for chips.

What shank size do I need?

The shank must fit your collet or tool holder. Most small end mills use a 1/8" or 1/4" shank. Larger end mills use 3/8" or 1/2" shanks. Always check your spindle collet size before ordering.

What is flute length vs. overall length?

Flute length is the cutting part of the tool. Overall length includes the shank. Use a flute length at least as long as your cut depth. Shorter flute lengths reduce deflection and chatter.

Should I use a fractional or metric end mill?

Match the end mill to your drawing units. If the part is in inches, use fractional sizes. If it is in millimeters, use metric. Mixing systems can cause tolerance errors on slot widths and pocket sizes.

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End Mill Size Chart

Notes on This Chart

Frequently Asked Questions

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