How do you calculate an instrument accuracy score?

Multiply the accuracy severity, occurrence, and detection ratings, each from 1 to 10. Ratings of 6, 3, and 4 produce the priority score in the worked example, flagging the instrument for review.

What is a good instrument accuracy score?

Lower scores are better and indicate accuracy that is unlikely to cause harm or go undetected. High scores from severe, frequent, hard-to-catch accuracy errors top the action list. Rank within your own fleet rather than against a fixed threshold.

What does the occurrence rating capture here?

It rates how often this instrument falls short of required accuracy, from 1 (consistently within spec) to 10 (frequently out of tolerance). The example uses 3 for occasional, infrequent accuracy issues.

How does the score guide accuracy upgrades?

High-scoring instruments justify higher-grade replacements or tighter calibration tolerances, while low-scoring ones can stay as-is. The score directs limited upgrade budget to the loops where measurement error matters most.

Why use severity times occurrence times detection?

The multiplicative FMEA structure ensures that a high rating on any single axis raises overall priority, so a severe-but-rare or undetectable accuracy problem still surfaces for attention.

Instrument accuracy score vs sensor drift risk: how do they differ?

Accuracy score targets an instrument's baseline measurement precision, while drift risk targets degradation over time. They share the severity-occurrence-detection method but point to upgrades versus recalibration respectively.

Industrial Sensors & Instrumentation calculator

Instrument Accuracy Risk Assessment Calculator

The Instrument Accuracy Score is an FMEA-style priority number that ranks how urgently an instrument's accuracy shortfall needs correction, combining severity, occurrence, and detection ratings. Metrology managers, process engineers, and quality teams use it to decide which instruments warrant tighter calibration tolerances, higher-grade replacements, or added verification. It matters because a marginally accurate instrument on a critical control loop can quietly push product off-spec, and ranking the fleet focuses upgrade budget where measurement error does the most damage. The score converts subjective accuracy concerns into a defensible, comparable priority.

What this calculator does

Score the risk of instrument inaccuracy using severity, occurrence, and detection ratings so teams can prioritize accuracy improvements, tighter specs, or measurement system upgrades.
Use this when conducting a measurement system risk assessment, comparing instruments for critical vs. non-critical loops, or deciding which measurement points justify higher-accuracy devices.
It multiplies accuracy severity, occurrence, and detection ratings into a single priority score that flags instruments needing tighter tolerances or upgrades.

Formula used

Accuracy risk score = severity rating x occurrence rating x detection rating
Higher scores identify instruments needing accuracy upgrades or tighter calibration tolerances.

Inputs explained

Accuracy severity rating:
Accuracy occurrence rating:
Accuracy detection rating:

How to use the result

Use it during measurement-system reviews, gauge R&R follow-ups, or when prioritizing which instruments to upgrade for accuracy.
Like any RPN, the score is ordinal and subjective, so equal scores can mask different risk profiles and ratings depend on reviewer judgment.

Current U.S. benchmarks

The producer price index for copper and brass mill shapes stands at 559.593 (BLS, May 2026), up 76.8% from a year earlier. Quotes priced off last quarter's material cost miss this move. Global copper trades at $13,484 per tonne (IMF via FRED, May 2026).
The U.S. has 11,261 computer and electronic products establishments employing about 815,443 workers (Census County Business Patterns, 2023).

Common questions

How do you calculate an instrument accuracy score? Multiply the accuracy severity, occurrence, and detection ratings, each from 1 to 10. Ratings of 6, 3, and 4 produce the priority score in the worked example, flagging the instrument for review.
What is a good instrument accuracy score? Lower scores are better and indicate accuracy that is unlikely to cause harm or go undetected. High scores from severe, frequent, hard-to-catch accuracy errors top the action list. Rank within your own fleet rather than against a fixed threshold.
What does the occurrence rating capture here? It rates how often this instrument falls short of required accuracy, from 1 (consistently within spec) to 10 (frequently out of tolerance). The example uses 3 for occasional, infrequent accuracy issues.
How does the score guide accuracy upgrades? High-scoring instruments justify higher-grade replacements or tighter calibration tolerances, while low-scoring ones can stay as-is. The score directs limited upgrade budget to the loops where measurement error matters most.
Why use severity times occurrence times detection? The multiplicative FMEA structure ensures that a high rating on any single axis raises overall priority, so a severe-but-rare or undetectable accuracy problem still surfaces for attention.

Last reviewed 2026-05-12.