SLA Calculator
Calculate allowed downtime for any SLA percentage, reverse-calculate an SLA from real downtime, and combine multiple dependent service SLAs into a composite uptime target.
Assumptions: one month = 30 days; quarter = 3 selected months; year = 365 days; day = 24 hours.
Other SLA presets
Other periods
Choose the measurement period and unit, then enter the observed downtime.
Equivalent rate in other periods
Series model: every service must be available. Assuming independent failures, composite availability = 100 × (SLA₁ / 100) × (SLA₂ / 100) × … . This is not a parallel/redundant architecture model and does not account for correlated failures.
Other periods
A provider SLA is a financial commitment, not a prediction of actual availability. This estimate does not calculate credits or contractual exclusions.
About the SLA calculator
A service level agreement expressed as a percentage is easier to reason about when you convert it into time. This page does that in three directions: allowed downtime for a given SLA, the SLA implied by an observed amount of downtime, and the composite figure you get when several services have to work together.
What the percentages mean (30-day month)
- 99.9% — about 43 minutes of downtime per month.
- 99.95% — about 21 minutes per month.
- 99.99% — about 4 minutes per month.
- 99.999% — about 26 seconds per month.
Why composite SLAs matter
When a request has to pass through several components in sequence, their availabilities multiply. An application gateway, a web app, and a database each at 99.95% give roughly 99.85% together — noticeably worse than any single component. Adding dependencies always lowers the ceiling, which is why redundancy inside a tier is worth more than another nine on paper.
Remember that a cloud provider's SLA is a financial commitment, not a prediction. Credits are paid when a target is missed; they do not restore your service or your data, and most SLAs exclude planned maintenance and customer misconfiguration.