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Vulnerability Health Score Calculator

Roll MTTP, SLA compliance, scan coverage, open criticals and backlog age into one 0–100 health score with a grade.

About Vulnerability Health Score Calculator

Speed and discipline carry half the score between them because they are what actually shortens exposure; coverage is next because a finding you never see cannot be counted in either. The two backlog terms are deliberately harsh — one critical open for a year drags the score more than a dozen opened last week — and the trend adjustment stops a snapshot from hiding a programme that is quietly losing ground. One defensible number that decomposes into five drivers is what gets vulnerability management onto a management dashboard without a fortnightly argument about which metric to show.

Formulas

Vulnerability Health Score

Health = 0.25 × MTTP component + 0.25 × SLA compliance + 0.20 × coverage + 0.15 × open-critical component + 0.15 × backlog-age component, plus a trend adjustment of ±8.

MTTP component
100 − 3 × days beyond a 7-day benchmark
open-critical component
100 − 2.5 per open critical
backlog-age component
100 − 0.8 per day the oldest critical exceeds 30
trend
±8 for a shrinking or growing backlog

Grade bands

Grades: 90+ A Excellent, 75–89 B Good, 60–74 C Fair, 40–59 D Weak, below 40 F Critical.

Worked example

With the default values below, Vulnerability Health Score Calculator returns Vulnerability Health Score of 65.5. Change any input above and every figure here is recalculated in your browser.

Inputs used

Critical MTTPaccepts 0–365 days
22 days
SLA complianceaccepts 0–100 %
78 %
Effective scan coverageaccepts 0–100 %
84 %
Open criticalsaccepts 0–100,000 findings
18 findings
Age of the oldest open criticalaccepts 0–3,650 days
95 days
Backlog trend over the last quarterone of Growing — −8, Flat — 0, Shrinking — +8
Flat — 0

Results

Vulnerability Health Score
65.5 / 100
Grade
C — Fair
MTTP Component
55.0 / 100
SLA Component
78.0 / 100
Backlog Age Component
48.0 / 100
Weakest Component
Backlog age — the oldest critical has been open 95 days
Headline
Struggling — fix the weakest component before adding scope

Step by step

  1. 1Values used
  2. 2Vulnerability Health Score
  3. 3Grade bands
  4. 4Vulnerability Health Score= 65.5 / 100
  5. 5Grade= C — Fair
  6. 6MTTP Component= 55.0 / 100
  7. 7SLA Component= 78.0 / 100
  8. 8Backlog Age Component= 48.0 / 100
  9. 9Weakest Component= Backlog age — the oldest critical has been open 95 days

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 Vulnerability Health Score calculated?

Health = 0.25 × MTTP component + 0.25 × SLA compliance + 0.20 × coverage + 0.15 × open-critical component + 0.15 × backlog-age component, plus a trend adjustment of ±8. Speed and discipline carry half the score between them because they are what actually shortens exposure; coverage is next because a finding you never see cannot be counted in either. The two backlog terms are deliberately harsh — one critical open for a year drags the score more than a dozen opened last week — and the trend adjustment stops a snapshot from hiding a programme that is quietly losing ground.

Why does Vulnerability Health Score matter?

One defensible number that decomposes into five drivers is what gets vulnerability management onto a management dashboard without a fortnightly argument about which metric to show.

What values do I need to enter?

This calculator takes 6 inputs: Critical MTTP, SLA compliance, Effective scan coverage, Open criticals, Age of the oldest open critical, Backlog trend over the last quarter. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.

Is a single score not an oversimplification?

On its own, yes. It works because every component is published alongside it, so the conversation moves straight to the weakest driver instead of stalling on methodology. Never report the score without its components.

Why is the MTTP benchmark seven days?

Because it matches the critical SLA most regulated organisations commit to, and it is achievable with automated patch orchestration. Change it if your own SLA differs — the component simply penalises three points per day beyond whatever benchmark you set.

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