How do you calculate a contamination risk score?

Multiply the three sub-scores: severity x likelihood x detection weakness. With 8 x 5 x 4 the raw product is 160, which the tool normalizes to a 5.95 risk score on its scale.

What is a good contamination risk score?

Lower is better. Scores in the bottom third of your scale are monitor-only; mid-range needs a planned control; top-third scores like a high product of severity and detection weakness demand immediate action regardless of likelihood.

Why use multiplication instead of adding the scores?

Multiplying makes a risk that is bad on all three axes escalate fast, which mirrors real contamination events where a severe, frequent, hard-to-detect hazard is far worse than the sum of its parts suggests.

What does the detection control weakness score mean?

It rates how poorly your current monitoring would catch the contamination before it reaches product. A high score means weak detection, so a 4 here signals controls you cannot fully rely on.

Contamination risk score vs FMEA RPN, are they the same?

They share the severity-occurrence-detection structure of an RPN, but this version is tuned for cleanroom contamination hazards and normalizes the output so scores stay comparable across assessments.

How often should I re-score contamination risks?

Re-score after any deviation, control change, or trend shift, and at least at each periodic risk review, because a fixed control or a worsening particle trend changes the detection and likelihood inputs.

Cleanroom & Contamination Control calculator

Contamination Risk Score Calculator

A contamination risk score is a single prioritization number that combines how bad a contamination event would be, how likely it is, and how poorly your current controls would catch it. Contamination-control engineers, microbiologists, and quality risk managers in pharma, medical device, and semiconductor cleanrooms use it as a focused FMEA-style RPN to rank where to spend remediation effort. It matters because cleanrooms generate dozens of candidate risks, from gowning breaches to filter integrity, and gut feel ranks them poorly. Scoring severity, likelihood, and detection weakness on a common scale forces an apples-to-apples comparison so the highest-leverage control gets fixed first.

What this calculator does

Score contamination-control risk using impact severity, event likelihood, and weakness of current detection controls.
a team needs to prioritize corrective actions for particle, viable, gowning, material-transfer, or cleaning risks for a contamination risk review
It multiplies severity, likelihood, and detection weakness into one comparable contamination risk priority number.

Formula used

Contamination Risk Score risk score = contamination impact severity score × contamination event likelihood score × detection control weakness score
Use the same scoring scale across comparable cleanroom and contamination-control risks.

Inputs explained

Contamination impact severity score:
Contamination event likelihood score:
Detection control weakness score:

How to use the result

Use it during a contamination-control risk assessment, a deviation review, or when ranking a backlog of remediation actions.
Multiplication can rank a moderate-everything risk above a catastrophic-but-rare one; always sanity-check very high severity items by hand rather than trusting the product alone.

Current U.S. benchmarks

Industrial electricity averages 8.66 cents per kWh across the U.S. (EIA, Apr 2026), up 5.5% from a year earlier. Energy-intensive steps carry this directly into unit cost.
U.S. manufacturing runs at 75.6% of capacity (Federal Reserve, May 2026). New factory orders are up 2.3% year over year (Census).

Common questions

How do you calculate a contamination risk score? Multiply the three sub-scores: severity x likelihood x detection weakness. With 8 x 5 x 4 the raw product is 160, which the tool normalizes to a 5.95 risk score on its scale.
What is a good contamination risk score? Lower is better. Scores in the bottom third of your scale are monitor-only; mid-range needs a planned control; top-third scores like a high product of severity and detection weakness demand immediate action regardless of likelihood.
Why use multiplication instead of adding the scores? Multiplying makes a risk that is bad on all three axes escalate fast, which mirrors real contamination events where a severe, frequent, hard-to-detect hazard is far worse than the sum of its parts suggests.
What does the detection control weakness score mean? It rates how poorly your current monitoring would catch the contamination before it reaches product. A high score means weak detection, so a 4 here signals controls you cannot fully rely on.
Contamination risk score vs FMEA RPN, are they the same? They share the severity-occurrence-detection structure of an RPN, but this version is tuned for cleanroom contamination hazards and normalizes the output so scores stay comparable across assessments.

Last reviewed 2026-05-12.