Speeds & Feeds Calculator - RPM, Feed Rate & Chip Load for Milling and Drilling
Calculate spindle RPM and table feed rate based on cutter diameter, material, and number of flutes
Free speeds and feeds screening worksheet for milling and drilling review. Enter cutter diameter, flute count, workpiece material row, depth of cut, and width of cut to calculate RPM, feed rate, chip load, and material-removal-rate prompts. The app uses the standard RPM, feed, and MRR formulas with local SFM and chip-load rows that remain source-gap presets. Treat the output as a shop starting prompt only: current toolmaker data, machine capability, holder balance, workholding, coolant, guarding, chip evacuation, and first-article feedback can require different values.
Calculate turning speeds and feeds for your lathe
Lathe Turning Calculator →Check metal removal rate and in-cut time with source warnings
Metal Removal Rate Calculator →Look up drill speeds and tap drill sizes
Drill & Tap Calculator →Check chip load per tooth before reviewing toolmaker data
Chip Load Calculator →How It Works
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Select Local Material Row
Choose a broad material row such as mild steel, aluminum, stainless, cast iron, brass, titanium, or plastic. These rows are local prompts, not approved tool catalog data.
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Enter Cutter Geometry
Input cutter diameter and flute count. The calculator converts SFM to RPM using RPM = (SFM × 12) / (pi × diameter).
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Enter Engagement
Add depth of cut and width of cut so the app can screen material removal rate and show slotting or drilling review prompts.
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Override With Source Data
Use custom SFM or chip load only when you have current toolmaker, shop-qualified, or engineering-reviewed values for the exact setup.
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Review Boundaries
Treat RPM, feed, chip load, MRR, and warning tiers as review prompts before checking machine limits, workholding, coolant, guarding, and first-article results.
Built For
- Manual mill operators screening RPM and feed before checking toolmaker data
- CNC programmers sanity-checking formula math before CAM and setup review
- Shop supervisors documenting local starting rows and source gaps
- Students and apprentice machinists learning the RPM/feed/chip-load relationship
- Job shops building preliminary prompts before qualified quote and process review
Assumptions
- RPM uses RPM = (SFM x 12) / (pi x diameter).
- Feed rate uses RPM x flutes x chip load per tooth.
- MRR uses width of cut x depth of cut x feed rate.
- Local material rows are source-gap prompts pending current toolmaker and shop validation.
Limitations
- Does not model chip thinning, chatter stability, deflection, horsepower, torque curve, tool wear, or thermal limits.
- Machine rigidity, spindle runout, holder balance, and workholding stiffness are not approved by the calculation.
- Tool grade, coating, chipbreaker, edge prep, coolant, and material condition can require different values.
- Safe machine operation, guarding, PPE, LOTO, chip control, and inspection acceptance remain outside the calculator.
References
- Sandvik Coromant - Milling formulas and definitions
- Kennametal - How to find feeds and speeds for your tools
- Machinery's Handbook 32nd Edition source pointer
- ASM Handbook Volume 16 Machining source pointer