# Bearing Load Calculator

Calculate bearing L10 life from dynamic load rating, applied load, and speed. Covers ball and roller bearings. Free bearing life calculator.

## What this calculates

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.

## Inputs

- **Bearing Type** — options: Ball Bearing, Roller Bearing — Ball bearings use exponent 3, roller bearings use exponent 10/3
- **Dynamic Load Rating (C)** (lbs) — min 1 — Basic dynamic load rating from the manufacturer catalog
- **Applied Load (P)** (lbs) — min 1 — Equivalent dynamic bearing load on the bearing
- **Shaft Speed** (RPM) — min 1, max 100000 — Rotational speed of the bearing inner ring

## Outputs

- **L10 Life** (million rev) — Basic rating life (90% reliability)
- **L10 Life** (hours) — Expected life at given speed
- **Load Ratio (C/P)** — Higher is better. Below 1 means overloaded.
- **Safety Margin** (%) — How much capacity remains above the applied load

## Details

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.

## Frequently Asked Questions

**Q: What does L10 life mean?**

A: L10 is the number of revolutions (or hours) at which 10% of a group of identical bearings will have failed due to fatigue. Put another way, 90% of bearings will last at least as long as the L10 life. It is the standard reliability benchmark used across the bearing industry (ISO 281).

**Q: Why do roller bearings have a different exponent than ball bearings?**

A: The life exponent is 3 for ball bearings and 10/3 for roller bearings because of the different contact geometry. Ball bearings have point contact (elliptical contact patch), while roller bearings have line contact (rectangular patch). The line contact distributes stress differently, which changes the fatigue life relationship.

**Q: How do I find the dynamic load rating for my bearing?**

A: The dynamic load rating (C) is listed in the bearing manufacturer's catalog, usually in kN or lbs. Look up the bearing by part number. For example, a standard 6205 deep groove ball bearing has a C rating of about 14.8 kN (3,327 lbs). Major catalogs: SKF, NSK, Timken, FAG, NTN.

**Q: What is a good L10 life for industrial equipment?**

A: It depends on the application. General machinery: 20,000-30,000 hours. Conveyor rollers: 40,000+ hours. Electric motors: 20,000-40,000 hours. Vehicle wheel bearings: 200,000+ miles. Critical or hard-to-replace bearings should target the higher end. Non-critical, easily replaced bearings can use lower targets.

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Source: https://vastcalc.com/calculators/construction/bearing-load
Category: Construction
Last updated: 2026-04-08