Use this page as a quick reference for the relationships behind the calculators. The tables are explanatory; the exact cutting-data value should still come from the actual tool and material source.
Metric RPM
RPM = (1000 × Vc) ÷ (π × D)Vc in m/min; D in mmImperial RPM
RPM = (12 × SFM) ÷ (π × D)SFM in ft/min; D in inMilling Feed
F = RPM × Z × fzZ = flute countFeed per Rev
f/rev = F ÷ RPMKeep units consistentChip Load
fz = F ÷ (RPM × Z)Feed per toothMilling MRR
MRR ≈ F × ae × apRectangular approximationCutting Time
t = distance ÷ feedUse matching distance/feed unitsTurning Feed
F = RPM × f/revCommon turning relationshipUnit check
Write the units beside every source value. Convert before applying the equation, not after the result has already been created.