How to use the bearing L10 rating life calculator
Enter the basic dynamic load rating C from the catalog, the equivalent dynamic load P on the bearing, and the shaft speed. The page returns the basic rating life in millions of revolutions and in hours, the equivalent number of days at continuous 24-hour running, and how far the life falls if the load is doubled. C and P must use the same unit, since only their ratio enters the equation.
The equations are L10 = (C/P)^p and L10h = (10^6 / (60n)) x (C/P)^p, with a life exponent of 3 for ball bearings and 10/3 for roller bearings. This is the form published as the basic rating life of the International Organization for Standardization ISO 281 family. The material consulted here is secondary and current as of October 2026, so checking the standard itself is recommended. Load ratings stay as user inputs taken straight from the manufacturer catalog, because no verified default values exist to offer in their place.
The modified rating life that reflects lubrication and contamination, and bearing selection itself, are not covered. This is a reference aid and does not replace design work; review by a qualified engineer is required.
Frequently asked questions
No. It is a statistical figure for the life that 90% of a population of identical bearings reaches. An individual bearing may run shorter or longer than that.
They are not. This equation is the basic rating life built only on the load ratio and the speed. The modified rating life that accounts for lubrication and cleanliness is a separate procedure and is not covered here.
It falls with the load ratio raised to the exponent. Doubling the load cuts a ball bearing to roughly one eighth of its life and a roller bearing to roughly one tenth.