Calculator Inputs
Example Data Table
| Sample | Model | Adjusted Base Life | Beta / MTBF | Mission Life | B10 Life | Reliability at Mission |
|---|---|---|---|---|---|---|
| Bearing Lot A | Weibull | 12,000 Hours | β = 1.80 | 8,000 Hours | 3,437.36 Hours | 61.76% |
| Drive Module B | Weibull | 18,000 Cycles | β = 2.40 | 10,000 Cycles | 7,047.82 Cycles | 73.18% |
| Control Relay C | Exponential | 25,000 Hours | MTBF = 25,000 | 4,000 Hours | 2,634.01 Hours | 85.21% |
Formula Used
B10 life is the life where 10% of units are expected to fail, meaning 90% remain reliable.
Weibull Formula
B10 = ηadj × [−ln(0.90)]1 / β
Bx = ηadj × [−ln(1 − x)]1 / β
R(t) = exp[−(t / ηadj)β]
ηadj = η × Adjustment Factor ÷ Safety Factor
Exponential Formula
B10 = −MTBFadj × ln(0.90)
Bx = −MTBFadj × ln(1 − x)
R(t) = exp(−t / MTBFadj)
MTBFadj = MTBF × Adjustment Factor ÷ Safety Factor
How to Use This Calculator
- Select the reliability model that matches your life data.
- Choose the life unit or define a custom unit name.
- Enter Weibull parameters or MTBF, depending on the selected model.
- Provide mission life, custom Bx level, and operating profile.
- Apply adjustment and safety factors for field conditions.
- Press the calculate button to view B10, Bx, mean life, and survival metrics.
- Use the export buttons to download the latest result as CSV or PDF.
Frequently Asked Questions
1. What does B10 life mean?
B10 life is the point where 10% of units are expected to fail. It is commonly used in bearings, durability testing, and quality reporting because it highlights early-life performance more clearly than average life alone.
2. When should I use the Weibull model?
Use Weibull when failure behavior changes over time. It is suitable for early failures, wear-out behavior, and life data that does not follow a constant failure rate.
3. When is exponential mode appropriate?
Exponential mode is appropriate when failures occur randomly with a roughly constant hazard rate. It is often used for electronics, repairable systems, and simplified screening studies.
4. Why is beta important in Weibull analysis?
Beta controls the hazard trend. A beta below one suggests infant mortality, near one suggests random failure, and above one indicates increasing wear-out as the product ages.
5. What is the difference between B10 and Bx?
B10 is a specific case of Bx. Bx simply means the life where x percent of the population has failed. B10 sets x equal to 10%.
6. Why use adjustment and safety factors?
These factors let you reflect tougher operating conditions, installation uncertainty, lubrication issues, or conservative design practice. They help turn laboratory estimates into more realistic planning values.
7. Can I use cycles instead of hours?
Yes. The calculator supports hours, cycles, distance, starts, and custom units. The formulas stay the same as long as every life input uses the same unit consistently.
8. Does a higher mean life guarantee a higher B10 life?
Not always. Two products can share similar mean life but have very different early-failure behavior. B10 is more sensitive to distribution shape and is often better for warranty-focused decisions.