When it comes to machining, nothing is more important than precision. Whether you are working in a professional machine shop, running CNC equipment, or doing small-scale DIY projects, the tool you choose determines the outcome. Among those tools, milling cutters hold a special place. They shape, cut, and refine metal or other materials into useful products with incredible accuracy.
But here’s the catch—milling cutters don’t come in one-size-fits-all. Their performance heavily depends on the right size. That’s where a milling cutter size chart becomes a handy reference. In this guide, we’ll walk through the basics of milling cutters, why sizes matter, common types and dimensions, and finally, provide a detailed size chart you can use as a quick reference in your workshop.
What is a Milling Cutter?
A milling cutter is a rotating cutting tool used in milling machines or machining centers to remove material from a workpiece. Unlike a drill bit that only cuts in one direction (downward), milling cutters can cut in multiple directions—sideways, upward, or even at complex angles.
These cutters come in different shapes and sizes depending on the type of milling operation—slotting, face milling, contouring, gear cutting, or finishing.
To put it simply:
A drill bit makes holes.
A milling cutter shapes surfaces.
Why Milling Cutter Size Matters
Imagine trying to cut a delicate groove using a massive cutter or finishing a large surface with a tiny tool—it just wouldn’t work. The size of the cutter affects:
Accuracy – Too big, and you risk overcutting. Too small, and it may take forever to finish the job.
Surface Finish – Larger cutters provide smoother finishes, while smaller cutters are ideal for intricate details.
Tool Life – Using the wrong size can cause excess wear, breakage, or overheating.
Efficiency – Choosing the right size ensures faster machining and lower production costs.
That’s why machinists and CNC programmers always refer to a milling cutter size chart before selecting tools.
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Standard Milling Cutter Dimensions
Most milling cutters follow standard dimensions, especially when it comes to:
Cutter Diameter (D) – The width of the cutter across its widest point.
Shank Diameter (d) – The part that fits into the machine spindle or tool holder.
Cutting Length (L1) – How deep the cutter can cut.
Overall Length (L2) – Full length from tip to end of the shank.
These four dimensions define whether a cutter is suitable for a particular machine or job.
Types of Milling Cutters
Before we dive into the chart, let’s quickly explore the main types of cutters you’ll encounter.
1. End Mills
Most common milling cutter.
Used for profiling, slotting, contouring, and plunging.
Available in flat, ball-nose, and corner-radius styles.
2. Face Mills
Large-diameter cutters.
Perfect for flat surface finishing and material removal.
3. Slab Mills
Long, heavy-duty cutters.
Best for large-scale metal removal.
4. Side-and-Face Cutters
Cut on the sides as well as the face.
Used for slotting and grooving.
5. Form Cutters
Custom-shaped for special profiles (e.g., gear cutting).
6. Shell Mills
Designed to be mounted on an arbor.
Useful for heavy machining tasks.
Each type has its own range of sizes, but end mills and face mills are the most widely standardized.
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Milling Cutter Size Chart
Here’s a general size chart for common milling cutters. Keep in mind, exact sizes vary by manufacturer, but these ranges are widely accepted in the machining world.
End Mill Size Chart (Metric and Imperial)
| Cutter Diameter (D) | Shank Diameter (d) | Cutting Length (L1) | Overall Length (L2) |
|---|---|---|---|
| 1 mm (0.039″) | 3 mm | 3–6 mm | 38–50 mm |
| 2 mm (0.078″) | 4 mm | 5–8 mm | 38–50 mm |
| 3 mm (0.118″) | 3–6 mm | 6–10 mm | 38–50 mm |
| 4 mm (0.157″) | 4 mm | 8–12 mm | 50 mm |
| 6 mm (0.236″) | 6 mm | 10–18 mm | 50–60 mm |
| 8 mm (0.315″) | 8 mm | 12–25 mm | 60–75 mm |
| 10 mm (0.394″) | 10 mm | 15–30 mm | 75–100 mm |
| 12 mm (0.472″) | 12 mm | 20–40 mm | 75–100 mm |
| 16 mm (0.629″) | 16 mm | 25–50 mm | 100–120 mm |
| 20 mm (0.787″) | 20 mm | 30–60 mm | 100–150 mm |
| 25 mm (0.984″) | 25 mm | 40–80 mm | 125–160 mm |
Face Mill Size Chart (Common Ranges)
| Cutter Diameter (D) | Insert Pockets | Cutting Depth | Typical Use Case |
|---|---|---|---|
| 40 mm (1.57″) | 3–4 inserts | 2–5 mm | Small surface finishing |
| 63 mm (2.48″) | 4–6 inserts | 3–6 mm | General face milling |
| 80 mm (3.15″) | 5–8 inserts | 4–8 mm | Medium to heavy milling |
| 100 mm (3.94″) | 6–10 inserts | 5–10 mm | Large surface finishing |
| 125 mm (4.92″) | 8–12 inserts | 6–12 mm | Heavy material removal |
| 160 mm (6.30″) | 10–16 inserts | 8–15 mm | Industrial applications |
Slot & Side Cutter Sizes
| Cutter Diameter (D) | Thickness (T) | Bore/Arbor Size |
|---|---|---|
| 50 mm (1.97″) | 3–6 mm | 16–22 mm |
| 63 mm (2.48″) | 4–10 mm | 22 mm |
| 80 mm (3.15″) | 5–12 mm | 22–27 mm |
| 100 mm (3.94″) | 6–15 mm | 27–32 mm |
Milling Cutter Size Chart PDF
This Milling Cutter Size Chart PDF provides machinists, engineers, and CNC users with quick reference tables for end mills, face mills, and slot cutters. Organized in a clear landscape format, it includes cutter diameters, shank sizes, cutting lengths, and typical applications. A handy guide for accurate tool selection, improved efficiency, and precise machining results.
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How to Choose the Right Milling Cutter Size
With so many options available, how do you know which size is right for your job? Here’s a simple checklist:
Match Cutter Diameter to Job Size
Small grooves → small cutters.
Wide surfaces → larger face mills.
Check Machine Compatibility
Ensure shank size matches your collet, chuck, or arbor.
Consider Cutting Depth
Always pick a tool with cutting length slightly greater than your required depth.
Material of Workpiece
Hard steels require sturdier, larger cutters.
Plastics or aluminum allow smaller, sharper tools.
Balance Speed and Feed Rates
A bigger cutter removes material faster but requires more machine power.
Smaller cutters are slower but offer higher precision.
Tips for Using Milling Cutters
Use proper lubrication: Reduces heat and extends tool life.
Avoid chatter: Secure your workpiece tightly to prevent vibration.
Select correct spindle speed: Refer to cutting speed charts for each material.
Don’t exceed tool limits: Overloading a cutter leads to breakage.
Inspect regularly: Worn or chipped cutters give poor results.
Real-Life Example: End Mill Selection
Let’s say you need to machine a 12 mm wide slot in an aluminum block. Which cutter would you choose?
End mill size: 12 mm diameter (flat end).
Cutting length: At least 20 mm (slightly more than slot depth).
Shank size: Must fit your machine holder, typically 12 mm.
If you mistakenly use a 20 mm end mill, the slot will be oversized. If you use a 6 mm mill, you’ll need multiple passes—wasting time and risking errors.
This is why size charts are essential—they save time and ensure precision.
Final Thoughts
A milling cutter size chart is more than just numbers—it’s a blueprint for precision machining. Whether you are selecting an end mill for a CNC project or a face mill for large-scale finishing, knowing the right sizes ensures better accuracy, longer tool life, and improved efficiency.
For machinists, hobbyists, and engineers alike, always keep a size chart handy. It’s a simple step that saves costly mistakes and makes your work smoother.
Next time you are in the workshop and reach for a milling cutter, remember: the right size is the difference between a rough cut and a masterpiece.
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FAQs:
What is a milling cutter size chart?
A milling cutter size chart is a reference table that lists cutter diameters, shank sizes, cutting lengths, and overall lengths for different tools. Machinists and CNC programmers use these charts to select the right cutter for accuracy, surface finish, and machine compatibility, ensuring smooth operations and reducing tool wear during machining projects.
Why is cutter diameter important in milling?
Cutter diameter directly affects precision, surface finish, and material removal rate. A small diameter allows detailed work and fine grooves, while larger cutters are ideal for heavy cuts and smooth surfaces. Using the right diameter prevents overcutting or wasted passes, making the process more efficient and extending the life of both the tool and machine.
How do I choose the correct shank size?
The shank size must match your machine’s tool holder or collet for safe and stable operation. If the shank is too small, it may slip during cutting; if too large, it won’t fit. Always check your machine’s spindle or chuck capacity before selecting a cutter to ensure proper fit, accuracy, and vibration-free performance.
What’s the difference between cutting length and overall length?
Cutting length (L1) is how deep the tool can cut into the material, while overall length (L2) measures the entire tool from tip to shank end. Cutting length impacts machining depth, and overall length affects tool rigidity. Choosing the right balance ensures smooth operations, avoids tool breakage, and helps achieve precise machining results consistently.
Can I use one cutter size for all materials?
No, because different materials require different cutter sizes and geometries. For example, aluminum can be cut efficiently with smaller, sharper cutters, while hard steel needs sturdier, larger cutters to withstand stress. Using one cutter size for all jobs risks poor finish, tool wear, and possible breakage. Always match cutter size with material type.
How often should milling cutters be replaced?
Milling cutters should be replaced when they show signs of dullness, chipping, or reduced performance. The frequency depends on usage, material hardness, cutting speed, and lubrication. Regular inspection is key. Worn cutters cause poor finish, increase machine load, and risk tool breakage. Replacing them on time ensures efficiency, accuracy, and protects your machine’s spindle.
Where can I find standard milling cutter sizes?
Standard milling cutter sizes are available in manufacturer catalogs, machining handbooks, and reference charts like the Milling Cutter Size Chart PDF. Many suppliers provide downloadable size charts for quick selection. These charts cover end mills, face mills, and slot cutters, helping machinists save time, reduce errors, and select the right cutter for every job.