Bearing Load Calculator
How long will a bearing last under your operating conditions? This calculator uses the standard L10 bearing life formula to estimate life in hours and millions of revolutions. Enter the catalog dynamic load rating (C), your applied load (P), and shaft speed to get the L10 life at 90% reliability.
The L10 life formula is L10 = (C / P)^p where C is the basic dynamic load rating, P is the equivalent applied load, and p is the life exponent. For ball bearings, p = 3. For roller bearings, p = 10/3 (about 3.33). The result is in millions of revolutions.
To convert to hours: L10h = (10^6 x L10) / (60 x RPM). For example, a ball bearing with C = 5,000 lbs and P = 1,000 lbs has an L10 of 125 million revolutions. At 1,750 RPM, that is about 1,190 hours. If you need longer life, choose a bearing with a higher C rating or reduce the load.
The L10 value means 90% of identical bearings will survive at least this long under the same conditions. The median life (L50) is about 5 times the L10 life. Some manufacturers publish adjusted life values (L10a) that factor in lubrication quality, contamination, and material improvements, which can increase the estimate significantly.