UptimePad

Uptime calculator

Type an uptime or SLA target to see how much downtime it allows each day, week, month, quarter and year, or switch direction and turn real downtime into an uptime percentage.

%

Allowed downtime at 99.9%
Per day1m 26.4s
Per week10m 4.8s
Per month43m 48s
Per quarter2h 11m 24s
Per year8h 45m 36s

A year is 365 days and a month is a twelfth of a year (30.42 days). Your provider may count calendar months instead.

How the numbers are worked out

Allowed downtime is the share of time the target leaves over, multiplied by the length of the period:

downtime = (1 - uptime% / 100) × period

At 99.9% the leftover share is 0.1%, so a 365-day year allows 0.001 × 8,760 hours = 8.76 hours, which is 8 hours 45 minutes 36 seconds. Working backwards, 45 minutes down in a 30.42-day month is 45 ÷ 43,800 minutes of the month, or 99.8973% uptime.

Two things change the answer in real contracts. Many SLAs measure each calendar month, so the same 99.9% allows 40m 19.2s in a 28-day February and 44m 38.4s in a 31-day month. SLAs also list exclusions from the uptime count, so read how your provider defines downtime before you compare figures.

More calculators and guides

99.9 uptimeWhat three nines allows in each period and in real calendar months, and what SLAs promise at that level.SLO and error budget calculatorError budget in minutes and requests, burn rate and the alerts to set.MTBF calculatorMTBF, MTTR, availability, failure rate, FIT and AFR from a failure log.Nines of availabilityThe full table from 99% to 99.9999%, and why the month length matters.SLA, SLO and SLIWhat each term means and how an error budget follows from the SLO.Composite availabilityChained services multiply. Redundant ones do not add up the way you hope.

Monitor it for realA calculator tells you the budget. Visual Sentinel checks your site around the clock and alerts you when it goes down, so you know when the budget is being spent.

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