Availability Calculator

Availability Calculator

Calculate how much downtime should be permitted in your Service Level Agreement or Objective.


"In general, for any software service or system you can think of, 100% is not the right reliability target because no user can tell the difference between a system being 100% available and, let's say, 99.999% available." - Ben Treynor

Availability Cheat Sheet

Availability level Downtime per year Downtime per quarter Downtime per month Downtime per week Downtime per day Downtime per hour
90% 36.52 days 9.13 days 3.04 days 16.80 hours 2.40 hours 6.00 minutes
95% 18.26 days 4.57 days 1.52 days 8.40 hours 1.20 hours 3.00 minutes
99% 3.65 days 21.91 hours 7.30 hours 1.68 hours 14.40 minutes 36.00 seconds
99.5% 1.83 days 10.96 hours 3.65 hours 50.40 minutes 7.20 minutes 18.00 seconds
99.9% 8.77 hours 2.19 hours 43.83 minutes 10.08 minutes 1.44 minutes 3.60 seconds
99.95% 4.38 hours 1.10 hours 21.91 minutes 5.04 minutes 43.20 seconds 1.80 seconds
99.99% 52.59 minutes 13.15 minutes 4.38 minutes 1.01 minutes 8.64 seconds 0.36 seconds
99.999% 5.26 minutes 1.31 minutes 26.30 seconds 6.05 seconds 0.86 seconds 0.04 seconds
Calculations are based on the average Gregorian year: 365.2425 days
Availability percentage (%)