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# How do I calculate the RPM's of a stepping motor?

Published date: 07 January 2020

Formula for calculating stepping motor speed.

Below is the RPM formula for steppering motor drives that use pulse signals to create motion.
RPM = a/360 * fz * 60

RPM = Revolutions per minute.
“a” = step angle
“fz” = pulse frequency in hertz

Example 1:  Drive step resolution is set for 1000 steps per revolution.
Find step angle: 360 (degrees of rotation) divided by 1000 (steps per revolution) = .36 (degrees of rotation per step)
With input frequency of 1000hz, .36 / 360 * 1000 * 60 = 60 rpm
Example 2: Drive step resolution is set for 500 steps per revolution.
Find step angle: 360 (degrees of rotation) divided by 500 (steps per revolution) = .72 (degrees of rotation per step)
With input frequency of 1000hz, .72 / 360 * 1000 * 60 = 120 rpm.

To find required frequency to meet desired speed we must find Fz:
RPM / ( (a/360) * 60) = Fz

Step 1. Divide step angle by 360:  .36/360 = .001,  then multiply by 60 (seconds) .001 * 60 = .06
Step 2. Divide desired speed by .06: Desired speed of 500 rpm’s.   Therefore ; 500 / .06 = 8333.33   ( 8333.33 is the frequency in hertz required to reach 500 rpm’s for drive set at 1000 steps per revolution)

Rev 1-7-20