TorqueMath

Bearing Life Calculator

Enter the load, speed and the bearing's load ratings from its catalogue page. Get the equivalent load, the rating life L10 in hours and years, the life at higher reliability, and the smallest dynamic rating that reaches your target, per ISO 281.

Bearing type
Load ratings (from the catalogue)
kN
kN
kN
kN
rpm
Reliability (a₁)
Machine (sets the target life)
h
h
a_ISO
1 = basic life. Clean oil at the right viscosity can give 2 – 10; dirty or thin lubricant 0.1 – 0.5. Take it from the maker's life calculator if you have it.
Load zone and rolling elements

Life at other loads and speeds

Typical required life

Rating life L10h that machine designers aim for. Click a row to use it as your target.

MachineL10h, hours

How it is calculated

Basic rating life to ISO 281. L10 is the life that 90% of a group of identical bearings reach before the first sign of fatigue. The exponent p is 3 for ball bearings and 10/3 for roller bearings.

Equivalent load P = X · Fr + Y · Fa (X, Y from Fa/Fr against e) Rating life L10 = (C / P)^p million revolutions In hours L10h = 10^6 · L10 / (60 · n) Modified life Lnm = a1 · aISO · L10h Required rating C_req = P · (60 · n · L_target / 10^6)^(1/p) Static safety s0 = C0 / P0, P0 = max(Fr, X0·Fr + Y0·Fa)

X and Y factors are the usual catalogue values for single bearings. Deep groove ball: e and Y follow f₀·Fa/C₀ with f₀ = 14. Angular contact 40°: e = 1.14. Tapered roller: e = 0.37, Y = 1.6 (check your series). Spherical roller: e = 0.25, Y₁ = 2.7, Y₂ = 4.0. Cylindrical roller: radial load only. Reliability factor a₁ (ISO 281): 90% 1.00, 95% 0.64, 96% 0.55, 97% 0.47, 98% 0.37, 99% 0.25. Static safety s₀ should be at least 1 for quiet running, 2 for shock loads.

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