THE NUMBERS, EXPLAINED
How to use this calculator.
Observed failure frequency is used as a fixed probability. Future detection assumes identical independent runs; this is not a confidence interval.
Start with your inputs
Enter failed runs (count), total repeated runs (count), future independent runs (count). Keep amounts in the units shown on each field. The example is a starting point, not a recommended value.
| Input | Example value |
|---|---|
| Failed runs (count) | 2 |
| Total repeated runs (count) | 10 |
| Future independent runs (count) | 2 |
A worked example
With the example inputs above, observed failure rate (%) is 20. Change the inputs to explore your own scenario.
| Result | Example answer |
|---|---|
| Observed failure rate (%) | 20 |
| At least one future failure (%) | 36 |
How this is calculated
Observed failure rate (%)
Divide failed runs by total runs.
At least one future failure (%)
Subtract the probability that every future run passes from one.
Symbols and units
- a
- Failed runs (count)
- b
- Total repeated runs (count)
- c
- Future independent runs (count)
Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.
Assumptions and limits
Observed failure frequency is used as a fixed probability. Future detection assumes identical independent runs; this is not a confidence interval.
Calculations use the values you enter. Blank or invalid inputs show an error instead of silently substituting zero. Results are displayed to useful precision; calculations retain the underlying numeric precision.
Questions about this tool
What does the result tell me?
Observed failure rate (%); At least one future failure (%). The result applies to the method and inputs described above. Check the units and assumptions before using it in a decision.
Why might another calculator differ?
Differences in units, rounding, timing or model definitions can produce different answers. Compare the input definitions and the method, rather than only the final number. For this tool: Observed failure frequency is used as a fixed probability. Future detection assumes identical independent runs; this is not a confidence interval.
Are my inputs stored or sent to AI?
Calculations on this page happen in your browser. The separate AI question finder sends its submitted conversation to OpenAI; these calculator fields are not sent. Favourites and recent tool names are stored locally. A shared link contains the inputs you choose to include.
Further reading
Background reading; this does not imply endorsement or independent review of SumFizz.
Review status
Software example and browser checks are recorded in our quality report. No external expert review is claimed. Created with coding assistance; calculations run as ordinary browser code.
Read the quality report →