Input Data
Enter loads, speed and life. Use advanced options for units, safety and detailed equivalent load factors.
Example data table
These examples show typical inputs and approximate results using the same calculation model with modest safety factors.
| Example | Type | Fr (kN) | Fa (kN) | Speed (rpm) | Life (hours) | Ka | a1 | Safety | Approx. C required (kN) | Suggested series |
|---|---|---|---|---|---|---|---|---|---|---|
| 1 | Ball | 5.0 | 1.0 | 1500 | 20 000 | 1.1 | 1.0 | 1.2 | ~32 | 6305 / 6306 |
| 2 | Roller | 15.0 | 6.0 | 750 | 40 000 | 1.3 | 1.0 | 1.3 | ~110 | 22210 / 22212 |
| 3 | Ball | 2.5 | 0.0 | 3000 | 10 000 | 1.0 | 1.0 | 1.1 | ~13 | 6204 |
Example of using this calculator
This example shows a preliminary selection for a ball bearing on an industrial shaft. Assume a conveyor drive shaft supported by one bearing at the motor end.
- Bearing type: ball bearing.
- Load unit: kN.
- Radial load Fr: 5.0 kN.
- Axial load Fa: 1.0 kN.
- Speed: 1500 rpm.
- Desired life: 20 000 hours.
- Application factor Ka: 1.1 (light shock).
- Reliability factor a1: 1.0.
- Safety factor on C: 1.2.
- Number of bearings sharing load: 1.
- Use X, Y factors: disabled (simple 1.2 rule).
Enter these values in the form and press Calculate bearing size. The calculator determines the base equivalent load from radial and axial components, applies the application factor, converts life to million revolutions and computes required dynamic rating with the chosen exponent. With the safety factor included, a required rating slightly above thirty kilonewtons is obtained. From the sample catalog table the tool suggests a medium duty deep groove series such as 6305 or 6306 as illustrative options. In practice you would confirm the final selection against a real manufacturer catalog and verify dimensions, limiting speed, lubrication and mounting constraints.
Formula used
This calculator estimates bearing size from combined loading, speed and target life using standard rolling bearing life relations. Loads are treated in kilonewtons internally, life in hours and speed in rpm.
- Unit conversion: input loads in N are divided by 1000 to obtain kilonewtons.
- Base equivalent dynamic load (simple model): \( P_{\text{base}} = F_r + 1.2 F_a \).
- Base equivalent load with X, Y (optional): \( P_{\text{base}} = X F_r + Y F_a \).
- Application factor: \( P' = P_{\text{base}} K_a \).
- Load sharing: if several bearings share the same load, \( P = \dfrac{P'}{z} \) where \( z \) is the number of bearings.
- Life in million revolutions: \( L_{10} = \dfrac{60 n L_h}{10^6} \).
- Reliability correction: \( L_{10,\text{corr}} = \dfrac{L_{10}}{a_1} \).
- Required dynamic rating (before safety): \( C_{\text{raw}} = P \, L_{10,\text{corr}}^{1/p} \), with exponent \( p = 3 \) for ball bearings and \( p = 10/3 \) for roller bearings.
- Required dynamic rating (with safety): \( C = C_{\text{raw}} S \) where \( S \) is the safety factor.
Actual bearing selection also considers misalignment, lubrication, temperature, internal geometry and detailed manufacturer X, Y factors. This tool supports transparent preliminary sizing and documentation.
How to use this calculator
- Select the intended bearing type and load unit for your data.
- Enter radial and axial loads, speed and desired operating life.
- Adjust application factor, reliability level and safety factor as required.
- Specify how many bearings will share the load in your arrangement.
- Enable X, Y factors if you have catalog-based equivalent load coefficients.
- Press Calculate bearing size to compute equivalent load, required rating and suggested series.
- Export results using Download CSV or Download PDF for reports and design records.
- Confirm final bearing choice against manufacturer catalogs and detailed application notes.