Weibull Reliability Calculator
Chance that a component is still working after a given time, the share failed, the failure rate and the B10 life, from the Weibull shape and scale parameters.
Results
The dashed line marks the value you entered.
What this tool does
The Weibull distribution is the workhorse of reliability engineering because its shape parameter β describes how things fail: below 1 the failure rate falls (early 'infant mortality'), at exactly 1 it is constant and random, and above 1 it rises as parts wear out — bearings typically come out around 1.5, wear-out failures higher still. The scale η is the time by which 63.2 % have failed, whatever β is. Take both from a fitted analysis of real failure data or the supplier's figures.
Formula
R(t) = e^(−(t ÷ η)^β) · h(t) = (β ÷ η)(t ÷ η)^(β − 1) · B10 = η (−ln 0.9)^(1/β)
Variables
| Symbol | Meaning | Unit |
|---|---|---|
bt | Shape parameter β | — |
et | Scale parameter η (characteristic life) | h |
t | Operating time | h |
R | Reliability (chance still working) | % |
F | Share failed by then | % |
HR | Failure rate at that time | /h |
B10 | B10 life (10 % failed) | h |
Worked example
- Shape parameter β1.5
- Scale parameter η (characteristic life)10,000 h
- Operating time5000 h
- Reliability (chance still working)70.219 %
- Share failed by then29.781 %
- Failure rate at that time0.000106066 /h
- B10 life (10 % failed)2230.8 h
Limitations
- The result is an estimate based only on the values you type. Real situations often include factors this calculator does not know about.
- The default values are typical reference figures, not measurements of your situation. Replace them with your own data whenever you have it.