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EC2 Health Score Calculator

Score an EC2 instance out of 100 on utilisation balance, disk queueing, status checks, patch age and backup coverage.

About EC2 Health Score Calculator

Utilisation is scored as distance from a target band rather than as more-is-better, because 5% CPU is a waste problem and 95% is a latency problem. Availability carries the heaviest weight since a failed status check is a real customer-visible event, and patch age is forgiven for the first 30 days to match a typical monthly maintenance cycle. The weakest sub-score is surfaced separately so the composite never hides a single critical failure behind five healthy dimensions. A single score makes fleet-wide comparison possible, but remediation always starts from the weakest dimension — a 78 caused by missing backups is far more urgent than a 78 caused by low CPU.

Formula

EC2 Health Score

score = 0.20 × CPU balance + 0.15 × memory balance + 0.15 × I/O + 0.25 × availability + 0.15 × patch currency + 0.10 × backup coverage.

balance
Distance from the ideal utilisation band, not raw utilisation
availability
Penalty of 15 points per failed status check
patch currency
Full marks up to 30 days, then 1.2 points per day

Worked example

With the default values below, EC2 Health Score Calculator returns Health Score of 85. Change any input above and every figure here is recalculated in your browser.

Inputs used

Average CPU utilisationaccepts 0–100 %
45 %
Average memory utilisationaccepts 0–100 %
62 %
Average disk queue depthaccepts 0–100 requests
1.4 requests
Failed status checks per monthaccepts 0–100 events
1 events
Days since last patchaccepts 0–3,650 days
42 days
Backup and snapshot coverageaccepts 0–100 %
90 %

Results

Health Score
85 / 100
Rating
B — Good
Weakest Area
CPU utilisation balance
Availability Sub-score
85
Patch Currency Sub-score
86
Resource Balance Sub-score
81.6

Step by step

  1. 1Values used
  2. 2EC2 Health Score
  3. 3Health Score= 85 / 100
  4. 4Rating= B — Good
  5. 5Weakest Area= CPU utilisation balance
  6. 6Availability Sub-score= 85
  7. 7Patch Currency Sub-score= 86
  8. 8Resource Balance Sub-score= 81.6

Assumptions and limits

  • The result is derived only from the 6 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 1 decimal place, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is EC2 Health Score calculated?

score = 0.20 × CPU balance + 0.15 × memory balance + 0.15 × I/O + 0.25 × availability + 0.15 × patch currency + 0.10 × backup coverage. Utilisation is scored as distance from a target band rather than as more-is-better, because 5% CPU is a waste problem and 95% is a latency problem. Availability carries the heaviest weight since a failed status check is a real customer-visible event, and patch age is forgiven for the first 30 days to match a typical monthly maintenance cycle. The weakest sub-score is surfaced separately so the composite never hides a single critical failure behind five healthy dimensions.

Why does EC2 Health Score matter?

A single score makes fleet-wide comparison possible, but remediation always starts from the weakest dimension — a 78 caused by missing backups is far more urgent than a 78 caused by low CPU.

What values do I need to enter?

This calculator takes 6 inputs: Average CPU utilisation, Average memory utilisation, Average disk queue depth, Failed status checks per month, Days since last patch, Backup and snapshot coverage. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.

Are the weights fixed by AWS?

No, they are a sensible default for a general-purpose fleet, not an AWS standard. If your workload is latency-critical, raise the availability and I/O weights; if it handles regulated data, backup coverage and patch currency deserve more. What matters is applying the same weights consistently across the fleet.

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