Feed Rate Calculator
Use this tool for common machining scenarios. Choose a method, enter your values, and get an estimated feed rate instantly.
What is feed rate?
Feed rate is how fast a cutting tool moves through material. In milling and drilling, feed rate is usually shown as mm/min or in/min. Getting this value right is one of the most important parts of machining setup because it directly affects tool life, finish quality, heat generation, and cycle time.
If your feed is too low, the tool may rub instead of cut, creating excess heat and dulling quickly. If your feed is too high, you risk chatter, poor finish, tool breakage, or overload alarms. The goal is a stable chip-making process: chips carry heat away, reduce rubbing, and improve consistency.
Core feed rate formulas
1) Milling (chip load method)
Feed Rate = RPM × Number of Flutes × Chip Load per Tooth
This is the most common formula for end milling and router work.
2) Drilling (feed per revolution)
Feed Rate = RPM × Feed per Revolution
For drilling, manufacturers often publish a feed per revolution value rather than a chip load per tooth.
3) Travel speed from observed motion
Feed Rate = Distance / Time
This is useful for checking actual machine movement against programmed values.
How to use this calculator
- Select the calculation type that matches your operation.
- Choose metric or imperial units.
- Enter your spindle speed and cutting inputs.
- Click Calculate Feed Rate to get the recommended feed.
- Adjust based on real cutting behavior (chip shape, sound, spindle load, and finish).
Example calculations
Example A: Aluminum milling
Suppose you run a 2-flute tool at 12,000 RPM with a chip load of 0.05 mm/tooth:
Feed = 12,000 × 2 × 0.05 = 1,200 mm/min
Example B: Wood routing in inches
With a 3-flute bit at 18,000 RPM and 0.002 in/tooth chip load:
Feed = 18,000 × 3 × 0.002 = 108 in/min
Example C: Drilling steel
If RPM is 900 and recommended feed per revolution is 0.12 mm/rev:
Feed = 900 × 0.12 = 108 mm/min
What affects the correct feed rate?
- Tool diameter: Larger tools can usually take higher loads.
- Flute count: More flutes increase feed rate at the same chip load.
- Material: Aluminum, steel, plastics, composites, and wood behave very differently.
- Tool material/coating: Carbide, HSS, and coatings change heat tolerance and wear behavior.
- Radial and axial engagement: Slotting needs a different strategy than light finishing passes.
- Machine rigidity: Benchtop routers need more conservative settings than industrial VMCs.
- Workholding quality: Poor clamping often looks like “bad speeds and feeds.”
Common mistakes to avoid
- Using a single feed rate for roughing and finishing.
- Ignoring manufacturer chip load recommendations.
- Reducing feed too much when increasing spindle speed.
- Confusing mm/tooth with mm/rev.
- Not accounting for flute count changes between tools.
Practical workflow for better results
Step 1: Start from tool data
Use your cutter manufacturer’s recommended chip load or feed per revolution as your baseline.
Step 2: Calculate and test
Calculate feed, run a short test cut, and inspect chips and finish. Stable chips and smooth sound usually indicate a healthy cutting zone.
Step 3: Tune in small increments
Adjust feed in 5–10% steps while watching spindle load and vibration. Keep notes so you can build a reliable internal feeds-and-speeds library.
Final note
A feed rate calculator gives you a strong starting point, not a final guarantee. Real-world performance depends on setup, machine condition, coolant, fixturing, and toolpath strategy. Use calculations to get close quickly, then optimize with controlled test cuts.