CNC CALCULATORS
RPM Calculator
Calculate spindle speed for a specified feed rate, chip load and flute count.
Input parameters
Results update as you type.
CALCULATED RESULT
THE FORMULA
RPM = feed rate ÷ (chip load × flute count)
Divide feed rate in millimeters per minute by chip load in millimeters per tooth and flute count to find revolutions per minute.
These tools calculate the values you supply. They do not recommend tool, material or machine parameters.
Solve the feed-per-tooth relationship for spindle speed
Spindle speed from supplied inputs
At 5400 mm/min, 0.15 mm/tooth and two flutes, RPM = 5400 ÷ (0.15 × 2) = 18000. This calculator uses chip load and feed, not a cutting-speed-and-diameter model.
Check the result in context
Use consistent inch or millimeter inputs. RPM does not change when display units change. A numerical result does not establish safe spindle limits or suitable material/tool parameters; check the equipment and tool manufacturer's guidance.