Motor Slip Calculator

About this calculator

An induction motor's rotor never quite catches up to the rotating magnetic field set up by the stator — that gap is called slip, and it's precisely what induces the current in the rotor that produces torque, so a small amount of slip is inherent to how the motor works at all. Slip is calculated as (synchronous speed − rotor speed) ÷ synchronous speed × 100%, where synchronous speed itself comes from Ns = 120f/p, based on the supply frequency f and the number of motor poles p.

This calculator takes the synchronous and actual rotor speeds and returns both the slip percentage and the slip speed in RPM. Electrical engineers and motor maintenance technicians use slip as a quick health indicator — it typically rises under heavier mechanical load and abnormally high slip readings can point to problems like worn bearings, rotor bar damage, or an undersized motor for its application.