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
Frequently Asked Questions
Learn More
How Speeds and Feeds Actually Work
SFM and chip-load fundamentals with local-row limits, toolmaker data, machine capability, workholding, coolant, and setup-review boundaries.
Tap Drill Sizes: Why 75% Thread Is Usually Wrong
The thread percentage myth, why 60-65% thread engagement is the practical sweet spot, tap type selection, tapping stainless, and how to extract a broken tap.
Lathe Turning: Planning the Cut Before Review
Lathe RPM, feed, theoretical finish, G96 vs G97, depth-of-cut planning, and the machine, tooling, workholding, inspection, and safety checks still needed.
Metal Removal Rate Planning Guide
MRR formulas for milling, turning, and drilling with source boundaries for local unit-HP rows, in-cut time, machine limits, and quote assumptions.
Chip Load Explained: How to Calculate and Optimize Chip Load for Milling, Drilling, and Turning
Complete guide to chip load per tooth calculation for milling, drilling, and turning. Covers chip thinning, material-specific recommendations, tool diameter influence, and how to dial in the perfect feed rate.
Machinability Ratings: What They Mean and How to Use Them
What machinability percentage means, how ratings are measured relative to AISI 1212, and how to translate them into real cutting parameters.
CNC G-Code Basics: What Every Machinist Should Know
Foundational CNC G-code and M-code knowledge for machine shop operators. Code structure, modal groups, program flow, and common codes for mills and lathes.
Surface Finish (Ra): How Feed Rate and Tool Radius Control Your Part Quality
How feed rate, tool nose radius, and cutting conditions determine surface finish. Ra vs Rz, common callouts, and when to machine vs grind.
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