Working resources / Unit arithmetic
Drilling Speed, Feed and Unit Calculator
Convert supplied cutting speed and feed per revolution into spindle rpm and feed speed, with metric and inch units.
Cutting speed → rpm and feed speed
Enter your own cutting data. The example button supplies assumed values for checking arithmetic.
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Switching units clears inputs so a number cannot silently change meaning. Results are rounded for display; exports include unrounded values. Entries stay in this page only.
Length conversion
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Use the selected tool’s cutting data as inputs. This calculator converts quantities; it does not select machining settings.
Formula and units
In metric units, n = 1000 × vc / (π × D), and vf = fn × n. Diameter D is in mm, cutting speed vc in m/min and feed fn in mm/rev. The result is rpm and mm/min. See the Sandvik Coromant drilling formula sheet.
In inch mode the inputs are converted to metric before calculation, then feed speed is converted back. NIST defines one inch as exactly 25.4 mm and one international foot as exactly 0.3048 m.
Read the gun drilling catalogue example before interpreting a cutting-data row. For load estimates, see power and torque.