Motor Slip Calculator

You put a tachometer on the shaft and got 1750 RPM. Is that normal for this motor? Motor Slip Calculator turns the supply frequency, the pole count and your measured speed into synchronous speed, slip RPM and slip percent — the numbers you actually need to write on the service ticket.

HOW IT WORKS
Pick 50 or 60 Hz, or type the output frequency if the motor runs from a VFD. Tap the pole count. Enter the shaft speed you measured under load. The slip percentage appears immediately, with the synchronous speed and slip RPM underneath it.

WHAT YOU GET
- Synchronous speed from Ns = 120 x f / P
- Slip in both RPM and percent
- Pole counts from 2 through 12
- Custom frequency entry for variable frequency drives
- A note on whether the slip sits inside the usual full-load range
- Saved records so you can compare the same motor over time, or two motors side by side
- Rename, duplicate and delete individual records

BUILT FOR THE FIELD
The whole calculation is one screen. No account, no sign-in, and the numbers work without a network connection. Every result shows the formula it came from, so you can check the work instead of trusting a black box.

Inputs that cannot produce a real answer are blocked before you get a wrong number. A measured speed above synchronous speed is not possible on an induction motor, so the app tells you the synchronous speed and asks you to check the pole count or the tachometer reading rather than printing a negative slip.

WHO IT IS FOR
Motor repair and rewind shops, HVAC technicians, plant maintenance electricians, and apprentices learning why a nameplate says 1750 and not 1800.

WHAT IT DOES NOT DO
This app reports speed and slip. It does not diagnose motor faults, judge efficiency, or assess whether a load is safe. Those calls belong to the person in front of the machine.

Decimal input accepts both a period and a comma, so European keyboards work as they should.