Motor Slip Calculator
Work out motor slip from synchronous and rotor speed.
Runs in your browser. Nothing is uploaded — your input is processed on this device and discarded when you close the tab.
Motor Slip Calculator
How to use this tool
- Enter the supply frequency and the number of poles.
- Enter the measured rotor speed in rpm.
- Press Generate to see the synchronous speed and slip.
Worked example
At 50 Hz with 4 poles the synchronous speed is 120 x 50 / 4 = 1500 rpm. A rotor speed of 1450 rpm gives a slip of 50 rpm, which is 50 / 1500 = 3.33%.
What this tool does not do / Limits
This is an estimate from the values entered for a standard induction motor at steady load. It is not a substitute for an electrician or the motor datasheet, and slip varies with load.
Frequently asked questions
Why can the rotor never reach synchronous speed?
An induction motor needs slip so the rotating field can induce current in the rotor; at synchronous speed there would be no induced current and no torque.
What does a high slip mean?
Slip rises with load, so an unusually high slip can point to overload, low voltage or a rotor problem.
Related tools
JSON Studio
Format, validate, minify, query and compare JSON in your browser, with precise line-and-column errors.
LiveRegex Tester
Test patterns against sample text with match highlighting, capture groups and a safe one-second timeout.
LiveSecurity Header and DNS Checker
Check HSTS, CSP and other security headers, TLS details, and DNS/email authentication records (SPF, DKIM, DMARC).
Live