End Mill Sizes Chart
Use this end mill sizes chart to compare common metric and inch carbide end mill sizes, including ONMY catalogue dimension codes D, d, L and H, metric sizes, inch sizes, ball radius and corner radius options.
ONMY supports standard and custom carbide end mills in square, ball nose, corner radius, long reach and micro tool designs for CNC milling applications.
Request a Size Recommendation View Size ChartWhat to Confirm Before RFQ
- ✓ D: cutting diameter or required slot width
- ✓ H: flute length and cutting depth
- ✓ L: overall length and reach requirement
- ✓ d: shank diameter and tool holder condition
- ✓ Ball radius, corner radius or flat end requirement
- ✓ Workpiece material, hardness, coating and quantity
Metric and Inch Carbide End Mill Sizes
End mill size selection affects slot width, corner clearance, cutting depth, tool rigidity, surface finish and tool life. A suitable size should be selected according to the part feature, workpiece material, machine condition and required tolerance.
ONMY catalogue drawings use D for cutting diameter, d for shank diameter, L for overall length and H for flute length. Ball nose end mills also require ball radius, while corner radius end mills require the R value.
- Metric carbide end mill sizes for common CNC machining applications
- Inch and fractional end mill size reference for drawing conversion
- Small diameter and custom size support through Micro End Mills or Custom End Mills
- Ball nose, corner radius, square and long reach size selection
- Custom carbide end mill sizes according to drawing or sample
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How to Read ONMY End Mill Dimensions
ONMY catalogue drawings use D, d, L and H to describe the main carbide end mill dimensions. Please use these codes when sending drawings, RFQs or tool size requirements.
D = cutting diameter, d = shank diameter, L = overall length, H = flute length
Cutting Diameter
D is the cutting diameter or flute diameter. It determines slot width, pocket corner clearance and the machined feature size.
Shank Diameter
d is the shank diameter. It must match the collet, holder or chuck and affects clamping stability and runout control.
Overall Length
L is the overall tool length. It affects reach, setup length and tool rigidity during CNC milling.
Flute Length
H is the flute length or cutting edge length. It should match the required cutting depth without making the tool unnecessarily weak.
Example format: D6 × H15 × d6 × L50 means 6mm cutting diameter, 15mm flute length, 6mm shank diameter and 50mm overall length.
Common Metric End Mill Sizes
The following chart lists common metric carbide end mill diameters used in CNC milling. Exact flute length, overall length, shank diameter and coating should be confirmed by RFQ.
| Cutting Diameter | Common Tool Direction | Typical Applications | Related Page |
|---|---|---|---|
| 0.5mm – 0.8mm | Micro end mills / custom micro tools | Fine details, micro slots, precision parts and small features. | Micro End Mills |
| 1mm | Small diameter square, ball nose or corner radius tools | Small slots, mold details, precision machining and fine features. | Micro End Mills |
| 1.5mm | Small diameter carbide end mills | Fine milling, small pockets, narrow grooves and small part machining. | Micro End Mills |
| 2mm | 2 flute, 3 flute, ball nose or custom small tools | Small slots, aluminum machining, light profiling and mold details. | 2 Flute End Mills |
| 2.5mm | Small diameter square or ball nose tools | Precision pockets, narrow profiles and small cavity machining. | Ball Nose End Mills |
| 3mm | 2 flute / 3 flute / 4 flute carbide end mills | General small feature milling, slotting and side milling. | Flute Count Guide |
| 4mm | Square, ball nose and corner radius end mills | General CNC milling, light pocketing and profiling. | Square End Mills |
| 5mm | Square, long edge or custom end mills | Metric part features, side milling and pocket milling. | Custom End Mills |
| 6mm | Common square, ball nose and corner radius size | General slotting, side milling, finishing and mold machining. | Carbide End Mills |
| 8mm | General carbide end mills | Side milling, pocketing, profiling and medium-duty machining. | Carbide End Mills |
| 10mm | Square, corner radius or long reach tools | Medium-duty side milling, roughing review and profile milling. | Long Reach End Mills |
| 12mm | General carbide end mills | Steel, stainless steel, aluminum and mold machining applications. | Stainless Steel End Mills |
| 16mm – 20mm | Larger diameter or custom tools | Higher material removal, side milling and application-specific machining. | Custom End Mills |
This table is a selection reference. Final dimensions should be confirmed by your drawing, material and machining condition.
Common Inch End Mill Sizes
Inch and fractional sizes are commonly used in drawings and imported machining projects. The decimal and metric conversions below help with initial tool selection.
| Fractional Size | Decimal Inch | Approx. Metric Diameter | Typical Tool Direction |
|---|---|---|---|
| 1/32 in | 0.0313 | 0.79mm | Micro end mill / custom small diameter tool |
| 1/16 in | 0.0625 | 1.59mm | Small diameter square or ball nose tool |
| 3/32 in | 0.0938 | 2.38mm | Small diameter end mill for slots and details |
| 1/8 in | 0.1250 | 3.18mm | Common small end mill size |
| 3/16 in | 0.1875 | 4.76mm | General small to medium end mill size |
| 1/4 in | 0.2500 | 6.35mm | Common general CNC milling size |
| 5/16 in | 0.3125 | 7.94mm | General pocketing and side milling |
| 3/8 in | 0.3750 | 9.53mm | Medium-duty milling and profiling |
| 1/2 in | 0.5000 | 12.70mm | Side milling, roughing review and finishing |
| 5/8 in | 0.6250 | 15.88mm | Larger diameter milling tools |
| 3/4 in | 0.7500 | 19.05mm | Large diameter or custom application review |
| 1 in | 1.0000 | 25.40mm | Large carbide end mill or custom tool review |
For inch-size projects, please send the drawing unit system and tolerance requirements to avoid conversion mistakes.
End Mill Size Converter
Use this quick converter to change end mill diameters between metric millimeters and inch sizes. The result is for reference only; final tool dimensions should follow your drawing and ONMY catalogue confirmation.
Metric to Inch
Enter an end mill cutting diameter in millimeters.
Inch to Metric
Enter a decimal inch or fraction size, such as 0.25 or 1/4.
End Mill Sizes by Tool Shape
Different tool shapes use different size information. A square end mill needs cutting diameter and flute length, while ball nose and corner radius end mills also need radius values.
Square End Mill Sizes
Confirm diameter, flute length, overall length and shank diameter for slots, pockets and shoulders.
View Square End Mills →Ball Nose End Mill Sizes
Ball nose tools require both tool diameter and ball radius for 3D contouring and mold finishing.
View Ball Nose End Mills →Corner Radius Sizes
Corner radius tools require diameter and R value such as R0.2, R0.5, R1.0 or custom radius.
View Corner Radius End Mills →Long Reach Sizes
Long reach tools need cutting length, neck length, shank length, overhang and workpiece access review.
View Long Reach End Mills →How ONMY Product Families Support End Mill Size Requests
ONMY end mill families can support standard and custom size requests across square, ball nose, corner radius, long edge, long shank and material-specific machining applications.
| Product Family / Series Direction | Size Request Direction | Typical Use | What to Send |
|---|---|---|---|
| HMQ-2E / HMQ-3E / HMQ-4E | Standard square end mill sizes | Slotting, side milling, flat-bottom pockets and shoulder milling. | Diameter, flute length, overall length, shank diameter and coating. |
| HMQ-2EL / HMQ-3EL / HMQ-4EL / HMQ-4EX | Long edge / extra-long edge sizes | Deeper side walls and longer cutting edge requirements. | Cutting depth, required flute length and rigidity limits. |
| HMQ-4EH / HMQ-4EG | Long shank / extra-long shank sizes | Deep cavity reach and hard-to-access features. | Reach, overhang, holder condition and cutting load. |
| HMQ-2B / HMQ-2BH | Ball nose diameter and ball radius | 3D contouring, mold machining and curved surface finishing. | Diameter, ball radius, flute length, reach and surface finish need. |
| HMQ-2R / HMQ-3R / HMQ-4R | Corner radius size and R value | Stronger cutting corner, side milling and semi-finishing. | Diameter, R value, material hardness and corner clearance. |
| Made to Order | Custom end mill size | Non-standard diameter, inch/metric conversion, special length or OEM tooling. | Drawing, sample, material, tolerance, quantity and packaging request. |
Product family examples are used for selection reference. Final manufacturability and dimensions should be confirmed by RFQ.
How to Choose End Mill Diameter and Length
The best end mill size is not always the largest or longest tool. Choose the diameter and length that meet the part feature while maintaining tool rigidity and chip evacuation.
| Machining Requirement | Recommended Size Direction | Selection Notes |
|---|---|---|
| Narrow slot or groove | Diameter close to the slot width | Confirm tolerance and whether multiple passes are needed for better finish. |
| Small precision feature | 1mm, 1.5mm, 2mm or custom micro end mill | Runout, clamping and conservative cutting parameters are important. |
| Flat-bottom pocket | Square end mill diameter based on pocket corner clearance | Check internal corner radius limits because an end mill cannot create a perfectly sharp inside corner. |
| 3D contouring or mold surface | Ball nose diameter and ball radius based on surface detail | Smaller ball radius gives finer detail but may require longer machining time. |
| Stronger edge requirement | Corner radius end mill with suitable R value | Larger radius can strengthen the edge but must fit the part corner geometry. |
| Deep cavity or deep wall | Shortest possible long reach or long shank tool | Long overhang increases deflection risk; review cutting depth, holder and machine rigidity. |
| Non-standard drawing | Custom carbide end mill size | Send the drawing, sample or CAD requirement for manufacturing review. |
Need a Non-Standard End Mill Size?
ONMY can review custom carbide end mill sizes according to drawing, sample or machining application. Custom options include diameter, flute length, overall length, shank diameter, ball radius, corner radius, coating, flute count, marking and packaging.
Continue Choosing the Right Carbide End Mill
After confirming the size, compare flute count, coating, workpiece material and tool shape.
Micro End Mills
Small diameter carbide tools for 1mm, 2mm, 3mm and precision machining requirements.
View Micro End Mills →End Mill Coatings Guide
Compare coatings for aluminum, stainless steel, hardened steel and high-temperature materials.
View Coatings Guide →How to Choose Carbide End Mills
Use a complete selection guide covering material, tool shape, flute count, size and coating.
View Selection Guide →Need Help Confirming End Mill Size?
Send us your tool size requirement and our team can review a suitable standard or custom end mill option. Please provide material, hardness, tool diameter, flute length, overall length, shank diameter, radius requirement, coating and quantity if available.
- Metric and inch carbide end mill sizes
- 1mm, 2mm, 3mm and other small diameter tools
- Square, ball nose and corner radius size support
- Long reach, long edge and long shank size review
- Custom carbide end mills according to drawing
Send Your Requirement
End Mill Sizes FAQ
What are common end mill sizes?
Common carbide end mill sizes include small metric diameters such as 1mm, 2mm and 3mm, general metric sizes such as 4mm, 6mm, 8mm, 10mm and 12mm, and inch sizes such as 1/8, 1/4, 3/8 and 1/2 inch.
How do I choose end mill diameter?
Choose the end mill diameter according to the slot width, pocket corner clearance, part geometry, workpiece material and required rigidity. For tight corners or small features, smaller diameters or custom tools may be required.
What is the difference between flute length and overall length?
Flute length is the cutting length of the tool, while overall length is the full tool length from tip to shank end. A longer overall length provides more reach, but excessive overhang can increase vibration and deflection.
What size end mill should I use for a 1/4 inch slot?
A 1/4 inch end mill can be used as a starting point for a 1/4 inch slot, but tolerance, material, tool deflection and finishing allowance should be reviewed before final selection.
How do I convert inch end mill sizes to metric sizes?
Multiply the inch size by 25.4 to get millimeters. For example, a 1/4 inch end mill is approximately 6.35mm. You can use the converter on this page for quick metric and inch size reference.
Do you provide 1mm, 2mm and 3mm end mills?
Yes. ONMY can support small diameter carbide end mills such as 1mm, 2mm and 3mm through standard or custom micro end mill options, depending on tool shape, material and coating requirement.
How do I choose ball nose end mill size?
For ball nose end mills, confirm both the tool diameter and ball radius. Smaller ball radius tools can produce finer surface details, while larger tools may be more stable and efficient for broader surfaces.
Can you make custom end mill sizes?
Yes. ONMY supports custom carbide end mill sizes according to drawing, sample or machining application, including diameter, flute length, overall length, shank diameter, ball radius, corner radius, coating and flute count.
