Uptime and SLA calculator
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What the usual targets allow
| Uptime | Per day | Per month (30 days) | Per year |
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Uptime is the share of time a service was working. The rest is downtime. Providers often promise a figure such as 99.9% in a service level agreement (SLA), and this page shows what that figure really allows. For how we measure uptime on this site, see uptime percentages explained.
Questions
What does 99.9% uptime mean?
It allows about 8 hours 46 minutes of downtime a year, or 43 minutes a month. This is often called "three nines".
Is 99.99% much better than 99.9%?
It is ten times stricter: about 52 minutes a year instead of nearly 9 hours. Each extra nine usually costs far more to achieve.
Does planned maintenance count as downtime?
It depends on the agreement. Many service level agreements exclude announced maintenance, so read the small print.