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SLA Uptime Guarantees in Minutes and Hours

I was curious about how many 9s in typical service level agreements translates into how much actual time is allowed by each level of guarantee. A quick Google didn’t yield any quick references, so I turned to Excel and am including it here for future reference. For example, if a service provider offers three 9s, or 99.9% uptime SLA guarantee, how much does that actually allow in terms of time unavailability? Calculated for a regular 365-day year (leap years get you a couple extra seconds), here are the results:

# of 9s SLA Guarantee Minutes of Downtime Hours of Downtime
2 99% 5256 87.6
3 99.9% 525.6 8.76
4 99.99% 52.56 0.876
5 99.999% 5.256 0.0876
6 99.9999% 0.5256 0.00876
7 99.99999% 0.05256 0.000876

So essentially what we’re looking at is that with a 99% guarantee, the provider is allowed a little over 3.5 days of downtime per year, a 99.99% SLA is allowed a little under 1 hour, and seven 9s (99.99999%) guarantees you just 3 seconds of downtime per year. Interesting from a customer perspective, and even more interesting from a provider’s perspective.

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  1. Another Joshua Lyman Another Joshua Lyman

    I googled my own name and found a link to your site sorry to comment at this section of your site i do not know what sla’s are. When i found your site and began to read about you it was as if i was reading something i had written myself your approach to life and your ideals are very much like mine and i am happy to see people out there have a similar outlook on life i can only hope to be as successful and happy as you appear to be! thank you for doing good with your name. I want also to do good in mine.

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