Bearing Life (L10) Calculator

Formula

• L10 (10⁶ rev) = (C / P)^p
• p = 3 for ball bearings, 10/3 for roller bearings
• L10 (hours) = L10 rev × 10⁶ / (N × 60)
• Lnm = L10 × a1 × a2 × a3

About this calculator

Part of our Mechanical Calculators collection. Beams, bolts, springs, gears, bearings, and core ME calculations.

How it works

Basic rating life L10 equals (C/P) raised to the life exponent, in millions of revolutions. Convert to hours using speed. Adjusted life applies reliability, material, and lubrication factors a1, a2, and a3. Use catalog C and P values from your bearing datasheet.

Enter your values in the inputs above and click CALCULATE. Results appear on the right without a page reload. No login and no server upload.

Worked example

Ball bearing, C = 45 kN, P = 8.5 kN, 1500 rpm, all adjustment factors = 1.

1. p = 3
2. L10 = (45 / 8.5)³ = 148.4 million rev
3. L10 hours = 148.4 × 10⁶ / (1500 × 60) = 1649 h

Result: Basic rating life L10 ≈ 1649 hours at 1500 rpm.

When to use

• Estimating bearing life during machine design
• Comparing bearing sizes for a given load and speed
• Applying reliability and lubrication adjustment factors

Limitations

• Uses ISO 281 basic dynamic rating model; not full ISO 16281 modified life
• Assumes equivalent load P already includes radial and axial components
• Contamination and misalignment effects are only via a2/a3 factors you enter

FAQ

What is L10 life?

L10 is the life that 90% of a bearing group is expected to exceed under the stated load and speed.

What are a1, a2, a3?

a1 is reliability (1.0 for 90% reliability), a2 covers material and operating conditions, a3 covers lubrication film thickness.