Risk Priority Number Calculator
FMEA ordinal risk priority number product of three independently established1–10codes, not calibrated probability, expected harm or automatic priority authority. Actual independently established compatible SI units/model context; conditional arithmetic, not code compliance, engineering design or safe operation approval.
Description
An FMEA risk priority number multiplies ordinal severity, occurrence and detection codes under a chosen scoring convention.
An FMEA risk priority number multiplies ordinal severity, occurrence and detection codes under a chosen scoring convention.1
This tool calculates the supplied product without calibrating probability, harm or an automatic action priority.
When to use Risk Priority Number Calculator
Use this tool to calculate the supplied product without calibrating probability, harm or an automatic action priority.
How to use Risk Priority Number Calculator and how it works
- Prepare callerSeverity, callerOccurrence, callerDetection, with the units, conventions and assumptions below.
- Enter the required fields and run Risk Priority Number Calculator.
- Read result.value using the output definitions below.
- Correct any rejected inputs and rerun; interpret the result within the stated model and its assumptions.
| Input field | Meaning | Value type | Requirement |
|---|---|---|---|
| callerSeverity | Caller Severity. Use the units and matching context stated in the calculation below. | number | Required; integer 1–1000000; finite; other constraints below |
| callerOccurrence | Caller Occurrence. Use the units and matching context stated in the calculation below. | number | Required; integer 1–1000000; finite; other constraints below |
| callerDetection | Caller Detection. Use the units and matching context stated in the calculation below. | number | Required; integer 1–1000000; finite; other constraints below |
Supply severity, occurrence and detection codes, each an integer from 1 to 10. Multiply the three codes to return the risk priority number. The tool does not assign these ordinal ratings or supply an action threshold; equal products can represent different risk profiles.
RPN=severity*occurrence*detection Apply the input ordering, units and branch conditions stated above.
| Output field | Meaning | Value type |
|---|---|---|
| result | Object containing the calculated or selected fields below. | object |
| result.value | Integer product of the three supplied 1-to-10 rating codes. | number |
{
"input": {
"callerSeverity": 2,
"callerOccurrence": 3,
"callerDetection": 4
},
"output": {
"result": {
"value": 24
}
}
}Limitations and assumptions
The calculation uses the supplied observations and model inputs. It does not collect measurements, select a reference population or coefficient, or establish that the model applies to the actual case. The stated branch conditions and output units remain part of the result.
All fields require explicit values. Unexpected fields, wrong types, nonfinite numbers and sparse arrays are rejected. Alignment, bounds and supported-token rules are explained above; extremely large inputs or nonfinite results can also fail. Input errors differ from successful false comparisons, unavailable-domain flags and empty match lists.
Alternative or Complementary methods
Use Fault Tree OR Gate Calculator for a complementary operation: An OR-gate probability can combine event probabilities by the complement-product rule when mutual independence holds.
Use Fault Tree AND Gate Calculator for a complementary operation: An AND-gate probability equals a product only when the supplied event model supports mutual independence.
References
-
Risk Priority Number Calculator — tool.io
Similar or alternative tools
- Fault Tree OR Gate Calculator
An OR-gate probability can combine event probabilities by the complement-product rule when mutual independence holds.
- Fault Tree AND Gate Calculator
An AND-gate probability equals a product only when the supplied event model supports mutual independence.