Mechanical Design

Bearing L10 Life

Standard bearing life calculations per ISO 281 — compute expected L10 life from a known bearing rating, or find the required dynamic load rating for a target service life.

Inputs

Results

L10 life

—

hours

L10 life

—

million revolutions

Load ratio (C / Pr)

—

dimensionless

Inputs

Results

Required rating (C)

—

lbs

Target life

—

million revolutions

C / Pr ratio

—

dimensionless

ISO 281 — Basic Rating Life

Ball bearings (e = 3, ref = 1M rev): L10 (rev) = (C / Pr)³ × 1   [millions of revolutions] Roller bearings (e = 10/3, ref = 90M rev): L10 (rev) = (C / Pr)10/3 × 90   [millions of revolutions] L10 (hrs) = L10 (rev) × 10⁶ / (60 × n) C = Pr × (L10_rev / Lref)1/e   [required rating]
C = basic dynamic load rating (lbs or kN) Pr = equivalent radial load n = rotational speed (rpm) e = load-life exponent (3 = ball, 10/3 = roller) Lref = reference life (1M rev = ball, 90M rev = roller) L10 = life at 90% reliability