How to calculate downtime

Turn an uptime percentage into the downtime it allows, with the formula and worked examples.

Allowed downtime by service level

Quick-pick SLA tier

Or choose from list

Or enter a custom % (overrides above)

Allowed downtime

Allowed downtime is the period length multiplied by (100 minus the uptime percentage), divided by 100. Work in minutes and the arithmetic stays simple: 1,440 minutes in a day, 43,200 in a 30-day month, 525,600 in a 365-day year.

Worth knowing

A worked example. For 99.9% over a 30-day month: 43,200 times 0.1, divided by 100, equals 43.2 minutes. That is the well-known "about 43 minutes a month" figure. Do the same with 525,600 and you get 525.6 minutes a year, or 8 hours 46 minutes.

Every service level at a glance

Uptime	Per day	Per week	Per month	Per quarter	Per year
90%one nine	2h 24m	16h 48m	3d	9d	36d 12h
95%	1h 12m	8h 24m	1d 12h	4d 12h	18d 6h
99%two nines	14m 24s	1h 40m	7h 12m	21h 36m	3d 15h
99.5%	7m 12s	50m 24s	3h 36m	10h 48m	1d 19h
99.9%three nines	1m 26s	10m 5s	43m 12s	2h 9m	8h 45m
99.95%	43s	5m 2s	21m 36s	1h 4m	4h 22m
99.99%four nines	9s	1m	4m 19s	12m 58s	52m 34s
99.999%five nines	1s	6s	26s	1m 18s	5m 15s

Other service levels

Compare the tiers

Every common service level, and the downtime each one allows per month.

90% 3d / month one nine 95% 1d 12h / month 99% 7h 12m / month two nines 99.5% 3h 36m / month 99.9% 43m 12s / month three nines 99.95% 21m 36s / month 99.99% 4m 19s / month four nines 99.999% 26s / month five nines

Calculators: Uptime calculator · SLA calculator · Downtime calculator · Availability calculator · Downtime cost calculator

Kostenlos starten. Keine Kreditkarte.

Uptime, Cron, Synthetic, Logs, RUM, Incidents und Statusseiten. Kostenlose Stufe bei jedem Produkt.

Kostenlos starten Preise ansehen