Uptime & SLA calculator

How much downtime does 99.9% uptime really allow? Turn an SLA percentage into minutes per day, month and year, and back.

Uptime percentage

The other way round

How much uptime is left after a given amount of downtime in a month?

Minutes down this month

Uptime	Per day	Per week	Per month	Per quarter	Per year
90%	2h 24m	16h 48m	3d 1h 3m	9d 3h 9m	36d 12h 36m
95%	1h 12m	8h 24m	1d 12h 31m	4d 13h 34m	18d 6h 18m
99%	14m 24s	1h 40m 48s	7h 18m 18s	21h 54m 54s	3d 15h 39m
99.5%	7m 12s	50m 24s	3h 39m 9s	10h 57m 27s	1d 19h 49m
99.9%	1m 26s	10m 5s	43m 50s	2h 11m 29s	8h 45m 58s
99.95%	43s	5m 2s	21m 55s	1h 5m 45s	4h 22m 59s
99.99%	9s	1m	4m 23s	13m 9s	52m 36s
99.999%	864 ms	6s	26s	1m 19s	5m 16s

What are “the nines”?: Shorthand for uptime: three nines is 99.9% (about 43 minutes of downtime a month), four nines 99.99% (about 4 minutes), five nines 99.999% (about 26 seconds).
Which month length is used?: An average month: a year of 365.25 days divided by 12, about 30.44 days. SLAs sometimes use the actual calendar month, which changes the numbers slightly.
Measure your real uptime: Spot Downtime checks your site around the clock and reports uptime for the last 24 hours, 7 days and 30 days, so you know whether you're meeting your SLA.

Checking by hand only tells you about right now. Spot Downtime checks your sites around the clock and alerts you by email, Slack or Discord.