Know exactly how much downtime your SLA allows.
Calculate allowed downtime for 99%, 99.9%, 99.99%, 99.999% and custom SLA targets — updates instantly as you type.
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Quick SLA reference
| Availability | Downtime / year | Downtime / month |
|---|
What does SLA uptime actually mean?
99% uptime
Allows roughly 3.65 days of downtime per year. Fine for internal tools or low-stakes services, but too loose for anything customer-facing and revenue-generating.
99.9% uptime ("three nines")
The most common SLA tier for SaaS products — about 8h 45m of downtime a year. Achievable with solid infrastructure and basic redundancy, without needing multi-region failover.
99.99% uptime ("four nines")
Just under an hour of downtime a year. Typically requires redundant infrastructure, automated failover, and real incident response processes.
99.999% uptime ("five nines")
Around 5 minutes of downtime a year. Reserved for telecom, critical infrastructure, and systems where outages carry severe financial or safety consequences.