Understanding SLA Uptime Percentages

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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