Bearing fault frequency calculator
Enter the bearing geometry and shaft speed to get BPFO, BPFI, BSF and FTF in Hz, in CPM and as orders of running speed. Free, no sign-up.
| Frequency | Hz | CPM | Orders |
|---|
The defaults are a 6205 deep groove ball bearing at 1480 rpm. Take the geometry from the bearing manufacturer's data; if they publish defect frequencies directly, prefer those.
Formulas used
BPFO = (n / 2) · fr · (1 − (d / D) · cos φ) BPFI = (n / 2) · fr · (1 + (d / D) · cos φ) BSF = (D / 2d) · fr · (1 − ((d / D) · cos φ)²) FTF = (fr / 2) · (1 − (d / D) · cos φ)
fr is the shaft speed in Hz (rpm / 60). The formulas assume a stationary outer race and a rotating inner race, the usual case. Real frequencies can differ by a percent or so because of slip and load. What each frequency means and how to find it in a spectrum: bearing fault frequencies explained.
Let Prism do this for every bearing.
Send us a week of vibration data and we show you which bearings need attention.