Speeds & Feeds Calculator
How to use the speeds and feeds calculator for spindle RPM, feed rate and chip load on any tool type.
One calculator for speeds and feeds
The Speeds & Feeds Calculator (open it at /tools?tool=feeds-speeds) is the one speeds and feeds tool: it combines the two earlier speed and feed calculators, which did the same job under two names. Results and the inputs most cuts need sit at the top; settings, guides, formulas and sources are further down. Old links open it with your values carried over.
Material, hardness and sliders
Pick the material, then use the Hardness / condition slider to step through the published conditions of that alloy (for example 4140 annealed, prehardened and 40-45 HRC); each step uses its own cited data row. The Speed and Feed sliders scale the starting values from 25% to 200%. Diameter, flutes, depth and width of cut have sliders as well as number fields.
Machine limits and shop data
Typing your machine's max RPM, spindle power, taper and max feed is free; the calculator caps the results and warns when a limit is hit. On a shop plan you can also pick a station's machine (the same machine profile the Planning Assistant uses for that station) and a tool from your Tool Library to fill the inputs, and save the result back to that tool.
What It Calculates
Pick the material, tool type, tool material and diameter. It returns spindle RPM (from surface speed and diameter, capped at your machine's max RPM), feed rate (RPM x chip load x flutes, or RPM x feed per rev for drills and reamers), chip load, power and material removal rate, with the published source for every starting value.
Your own speed and feed
Under Overrides you can type your own SFM and chip load (or feed per rev). They replace the starting data, and the result is marked as your values. Chip thinning, the feed override and the machine RPM cap still apply.
Formulas Used
RPM = (SFM x 12) / (pi x Diameter). Feed Rate (IPM) = RPM x Feed per Tooth x Number of Flutes. Metric: Vc (m/min) = SFM x 0.3048 and n = 1000 x Vc / (pi x D).
Interpreting Results
Results update as you type. If the RPM is capped by your machine, the surface speed shown drops and the chip load is kept. Starting values come from published charts; the tool maker's data, your machine and your workholding win.