The table below helps illustrate why you should ensure that the “SLA Uptime Measurement Meter Reset Window” is the same duration as your billing cycle or shorter.
| Availability % | Downtime per year | Downtime per month (30 days) | Downtime per week | Downtime per day | |||||
| 90 | “one nine” | 36.5 | days | 72 | hours | 16.8 | hours | 2.4000 | hours |
| 95 | 18.25 | days | 36 | hours | 8.4 | hours | 1.2000 | hours | |
| 97 | 10.96 | days | 21.6 | hours | 5.04 | hours | 43.2000 | minutes | |
| 98 | 7.3 | days | 14.4 | hours | 3.36 | hours | 28.8000 | minutes | |
| 99 | “two nines” | 3.65 | days | 7.2 | hours | 1.68 | hours | 14.4000 | minutes |
| 99.5 | 1.83 | days | 3.6 | hours | 50.4 | minutes | 7.2000 | minutes | |
| 99.8 | 17.52 | hours | 86.23 | minutes | 20.16 | minutes | 2.8800 | minutes | |
| 99.9 | “three nines” | 8.76 | hours | 43.8 | minutes | 10.1 | minutes | 1.4400 | minutes |
| 99.95 | 4.38 | hours | 21.56 | minutes | 5.04 | minutes | 43.2000 | seconds | |
| 99.99 | “four nines” | 52.56 | minutes | 4.32 | minutes | 1.01 | minutes | 8.6400 | seconds |
| 99.999 | “five nines” | 5.26 | minutes | 25.9 | seconds | 6.05 | seconds | 0.8640 | seconds |
| 99.9999 | “six nines” | 31.5 | seconds | 2.59 | seconds | 0.605 | seconds | 0.0864 | seconds |
| 99.99999 | “seven nines” | 3.15 | seconds | 0.259 | seconds | 0.0605 | seconds | 0.0086 | seconds |
Sources: Wikipedia, my calculations
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