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Platform Reliability Score Calculator

Generate an overall platform reliability score from uptime, incidents and SLO adherence.

About Platform Reliability Score Calculator

This composite score blends four reliability signals into a single weighted number: availability (40% weight, since uptime is the most visible reliability signal), MTTR (25%, rewarding fast recovery), incident rate (20%, penalizing frequent instability), and error budget consumption (15%, reflecting SLO health). Each sub-score is normalized to 0-100 before weighting, and the final score maps to a letter grade (A: 95+, B: 85+, C: 70+, D: 50+, F: below 50).

Formulas

MTTR sub-score

mttr_score = max(0, 100 - (mttr_hours / 24) × 100)

mttr_hours
Mean Time to Recovery in hours

Overall reliability score

score = availability × 0.4 + mttr_score × 0.25 + incident_rate_score × 0.2 + budget_score × 0.15

availability
Measured availability percentage (0-100)
mttr_score
MTTR sub-score (0-100)
incident_rate_score
max(0, 100 - incidents_per_month / 20 × 100)
budget_score
max(0, 100 - error_budget_consumed_percent)

Worked example

With the default values below, Platform Reliability Score Calculator returns Platform Reliability Score of 89.4. Change any input above and every figure here is recalculated in your browser.

Inputs used

Availabilityaccepts 0–100 %
99.9 %
MTTRaccepts 0–1,000 hours
1.5 hours
Incidents per Monthaccepts 0–1,000 incidents
3 incidents
Error Budget Consumedaccepts 0–500 %
40 %

Results

Platform Reliability Score
89.4
Reliability Grade
B
Availability Sub-Score
99.9
MTTR Sub-Score
93.8
Incident-Rate Sub-Score
85.0
Error-Budget Sub-Score
60.0

Step by step

  1. 1Availability score (40% weight)= 39.96
  2. 2MTTR score (25% weight)= 23.44
  3. 3Incident-rate score (20% weight)= 17.00
  4. 4Error-budget score (15% weight)= 9.00
  5. 5Overall reliability score= 89.4 (B)

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax or fees or charges 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

Why is availability weighted highest?

Availability is the most direct, universally understood measure of whether users can access the service, so it carries the largest weight (40%) while the other signals capture how well incidents are handled and how much reliability margin remains.

How are the MTTR and incident-rate sub-scores normalized?

MTTR score linearly decays from 100 (instant recovery) to 0 at a 24-hour resolution time; incident-rate score linearly decays from 100 (zero incidents) to 0 at 20 incidents/month — both are heuristic reference points and can be recalibrated to your organization's norms.

Can this replace SLO reporting?

No — this is a simplified composite scorecard useful for at-a-glance comparisons across teams or time periods. Formal SLO compliance should still be tracked per-service against its specific SLI/SLO definitions.

What should a team do with a 'D' or 'F' grade?

Treat it as a signal to prioritize reliability work: identify which sub-score is dragging the total down (e.g. high incident rate vs. slow MTTR) and target that specific area — a low incident-rate score points to stability work, while a low MTTR score points to on-call/runbook improvements.

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Platform Reliability Score Calculator | Calcrivo