Criticality Matrix Calculator
Score consequence and likelihood on a 5×5 matrix to find an asset's criticality band
Inputs
Score the worst credible outcome of this asset failing in its current duty. The scales are an example. Replace the anchors with your own before relying on the ranking.
Consequence
4 of 5
Driven by production
Criticality
12 of 25
High criticality
Risk matrix
| 5 Almost certain | 5 | 10 | 15 | 20 | 25 |
|---|---|---|---|---|---|
| 4 Likely | 4 | 8 | 12 | 16 | 20 |
| 3 Possible | 3 | 6 | 9 | 12 | 15 |
| 2 Unlikely | 2 | 4 | 6 | 8 | 10 |
| 1 Rare | 1 | 2 | 3 | 4 | 5 |
| 1 | 2 | 3 | 4 | 5 |
Rows are likelihood, columns are consequence. High from 12, medium from 5. A safety or environmental consequence of 5 is always high.
What a high rating sets
- Full FMECA and RCM decision logic
- Condition monitoring justified
- Engineered spares
- Review after every incident
How it's calculated
Consequence
Worst of safety, environment, production and cost
Likelihood
How often the failure is expected
Criticality
Consequence × likelihood
Band
High, medium or low, and the strategy it sets
Consequence = the highest of the four category scores, so one severe outcome is never diluted by three mild ones.
Criticality = consequence × likelihood, a score from 1 to 25.
Band = high from 12, medium from 5, low below that. A safety or environmental consequence of 5 is high whatever the likelihood.
How to use a criticality matrix: a worked example
Take the lubrication pump on a primary crusher, with no standby unit, using the values the calculator opens with. The pump itself is cheap, but if it fails the crusher stops, so the production consequence is severe.
| Step | Score | Why |
|---|---|---|
| Safety | 2 | Recovery work carries a risk of injury needing medical treatment |
| Environment | 1 | An oil leak stays contained inside the crusher building |
| Production | 4 | The crusher is down for more than a shift while the pump is replaced |
| Cost | 3 | Emergency replacement, call-out labour and possible crusher bearing damage |
| Consequence | 4 | The highest of the four, driven by production |
| Likelihood | 3 | Expected about once in 2 to 5 years in this duty |
| Criticality | 12 | 4 × 3, which lands in the high band |
Put the same pump in a duty and standby pair and its production and cost scores fall to 2. Nothing about the pump has changed, only its duty, and it drops from the high band to medium.
How the score is calculated
Each consequence category is scored separately against its own anchors, and the asset's consequence is the highest of the four. Taking the highest rather than an average stops one severe outcome being diluted by three mild ones, which is the most common way a critical asset ends up ranked as ordinary.
Criticality is consequence multiplied by likelihood, a score from 1 to 25. The bands used here start at 12 for high and 5 for medium. A catastrophic safety or environmental consequence is high regardless of likelihood, because no failure rate makes a fatality or major environmental harm acceptable.
| Band | Score | Strategy depth | What else changes |
|---|---|---|---|
| High | 12 to 25, or a 5 for safety or environment | Full FMECA and RCM decision logic | Condition monitoring justified, Engineered spares, Review after every incident |
| Medium | 5 to 11 | Template strategies tuned per equipment class | Monitoring by exception, Spares set from lead time and pooling |
| Low | 1 to 4 | Run to failure where that is honest | Minimal stocking, No scheduled intrusive work |
The example scale, as a template
The calculator uses the scale below. It is anchored to outcomes rather than adjectives, so two people scoring the same asset reach the same number. Treat it as a template. Production hours, cost thresholds and likelihood ranges should come from your own operation, and the whole scale should sit inside the corporate risk framework, which usually follows ISO 31000. Published schemes such as the consequence classes in NORSOK Z-008 are a useful cross-check.
| Level | Safety | Environment | Production | Repair and consequential cost | Likelihood |
|---|---|---|---|---|---|
| 1 | No injury, or first aid only | No impact | No production loss | Under $5,000 | Rare, less than once in 10 years |
| 2 | Medical treatment | Minor, contained on site | Under 1 hour, or a spared unit | $5,000 to $50,000 | Unlikely, once in 5 to 10 years |
| 3 | Lost time injury | Reportable, short term | 1 to 8 hours lost | $50,000 to $250,000 | Possible, once in 2 to 5 years |
| 4 | Serious or permanent injury | Significant, off site | 8 to 48 hours lost | $250,000 to $1 million | Likely, about once every 1 to 2 years |
| 5 | Fatality | Major, long term harm | More than 48 hours lost | More than $1 million | Almost certain, more than once a year |
Running an assessment with it
A calculator scores one asset at a time. A site assessment needs the same scale applied consistently across hundreds, which is a workshop problem as much as a scoring one, and the asset criticality assessment guide covers running it in depth.
- Score systems, not tags. Rank at the level where the consequence is felt, such as the crusher lubrication system, and let the components inherit the result.
- Put operations, maintenance and engineering in the same room. Each group on its own scores its own concerns.
- Fix the scales before the first asset is scored, and do not renegotiate them halfway through.
- Record the reasoning with every score. The register template has a column for it, and the next review will need it.
- Watch the distribution. If most assets land in the high band, the scales are too generous and the ranking cannot ration anything.
- Reassess on triggers such as a change of duty, a design change or a significant incident, not only on a calendar.
Why it matters
No maintenance budget stretches to giving every asset the same attention. Criticality is how the effort gets rationed honestly. Deep analysis, condition monitoring and engineered spares go to the equipment whose failure hurts most, and lighter strategies cover everything else.
The ranking only earns its keep when each band changes what happens next. A register where most assets score high, or where a band carries no consequence for strategy, spares or monitoring, is a spreadsheet rather than an assessment.
Common questions
What is a criticality matrix?
A criticality matrix plots the consequence of an asset failing against the likelihood of that failure, usually on a 5 by 5 grid. Each cell carries a score, consequence multiplied by likelihood, and the scores are grouped into bands that set how much maintenance attention the asset receives.
How is asset criticality calculated?
Score the consequence of failure in each category, typically safety, environment, production and cost, against anchored scales, and take the highest. Score the likelihood of failure on its own scale. Criticality is consequence multiplied by likelihood, and the result is grouped into high, medium and low bands.
Should consequence scores be added together or should the highest be used?
Most schemes take the highest, because adding or averaging lets one severe outcome be diluted by several mild ones. An asset with a fatality risk and no production impact should never rank below one with moderate scores everywhere.
Is there a criticality assessment template?
Yes. The calculator's register template downloads as a CSV with columns for each consequence category, likelihood, score, band, strategy and reasoning, plus the example scale. It opens in Excel or any other spreadsheet.
How many criticality bands should there be?
Three is usually enough, because each band has to change something, such as the depth of strategy analysis, the monitoring or the spares holding. More bands than the organisation can treat differently add argument without adding decisions.
How often should criticality be reassessed?
On triggers rather than only on a calendar. Reassess when an asset's duty changes, after a design change or plant modification, after a significant incident, and at a periodic review so that gradual change does not accumulate against a frozen ranking.
Related reading
- Running an asset criticality assessment that holds up
- Reliability centred maintenance, and when criticality-led beats it
- Condition monitoring: techniques, intervals and building a program that works
- Reliability engineering and asset strategy program
- Cost of Downtime Calculator
- FMECA: how to run a failure modes, effects and criticality analysis
Want to improve the numbers?
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