Weibull reliability calculator
The chance a part or machine survives to a given age, its B10 life and mean life, from the Weibull shape (beta) and scale (eta) of its failures.
Your numbers
Weibull parametersQuestion See your resultResult
Reliability at 500 h 88.2%chance it hasn’t failed by then; 11.8% that it has B10 life 446 hage by which 10% have failed Mean life (MTTF) 1,805 hη × Γ(1 + 1/β) Failure rate at 500 h 0.375 per 1,000 hrising with age: wear-out Stop working this out by handFleetZap’s reports work out MTBF for every machine from the work orders your team closes, so you have real failure history to work from.
See FleetZap Maintenance · Try the demoThe formula
Reliability R(t) = e^−(t ÷ η)^β · B10 = η × (−ln 0.9)^(1/β) · Mean life = η × Γ(1 + 1/β)
With beta 1, Weibull is the exponential model behind MTBF, and reliability is e^(−t ÷ MTBF). With the example (beta 1.5, eta 2,000 h): 88.2% survive to 500 hours, B10 life is about 446 hours and mean life about 1,805 hours. Beta and eta come from fitting your own failure ages; ten or more failures of the same part give a usable fit. The reliability-centered maintenance guide explains how to act on it.
Using the numberWhat to do with it
- Beta over 1 means the part wears out: a time-based replacement before B10 can prevent most failures.
- Beta near 1 means failures are random: replacing early doesn’t help; condition checks and spares on the shelf do.
- Beta under 1 points at installation, quality or break-in problems, not at age.
Guides behind this calculator
Reliability-centered maintenance Maintenance and reliability What is MTBF?More free calculators
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The heart of FleetZap, and everything a maintenance team needs in one place: work orders and preventive maintenance, inspections and the field app, plus a parts store with purchasing, compliance and certificate tracking, multi-location assets with a full lifecycle, and the KPIs that prove it’s working.
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Good to know
What do the Weibull beta and eta mean?Beta (shape) says how failures behave: under 1 early failures, 1 random, over 1 wear-out. Eta (scale) is the characteristic life, the age by which about 63.2% have failed.
What is B10 life?The age by which 10% of a population has failed, so 90% survive. It's a common way to set replacement intervals for wearing parts.
How is Weibull related to MTBF?With beta equal to 1, the Weibull model becomes the exponential model, where reliability is e^(−t ÷ MTBF) and the failure rate is constant.
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