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Uptime Calculator
Translate an uptime guarantee into real time. Enter an SLA percentage such as 99.9% to see the downtime it allows per day, week, month and year — or enter an outage you measured to see what uptime percentage it works out to.
- Downtime per month
- 43 min 48 s
- Downtime per week
- 10 min 5 s
- Downtime per day
- 1 min 26 s
- Uptime
- 99.9%
Saved setups
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Your recent calculations
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Formula
How to use it
- Choose whether to start from a percentage or from an amount of downtime.
- Enter the SLA percentage, or the downtime and the period it occurred in.
- Read the allowed downtime for each period.
Worked examples
99.9% uptime: 0.1% of a 365-day year is 31,536 seconds, or 8 h 45 min 36 s
- Downtime per year
- 8 h 45 min
- Downtime per month
- 43 min 48 s
- Downtime per week
- 10 min 5 s
- Downtime per day
- 1 min 26 s
99.99% uptime: 52 min 33.6 s a year
- Downtime per year
- 52 min 34 s
- Downtime per month
- 4 min 23 s
- Downtime per week
- 1 min
- Downtime per day
- 8.64 s
30 minutes of downtime in a month (1,800 s of 2,628,000 s)
- Uptime
- 99.9315%
- Downtime per year
- 6 h
The nines
99% (“two nines”) allows 3.65 days of downtime a year. 99.9% allows 8 hours 45 minutes 36 seconds. 99.95% allows 4 hours 22 minutes 48 seconds. 99.99% allows 52 minutes 34 seconds. 99.999% (“five nines”) allows just 5 minutes 15 seconds.
Read the SLA’s small print
Providers differ on what counts. Many measure per calendar month, exclude scheduled maintenance, count only outages longer than a set number of minutes, and pay service credits rather than refunds. Two services with the same percentage can make quite different promises.
Availability multiplies
A system that depends on several components in series is only as available as their product. Three services at 99.9% each give 99.7% together — about 26 hours of downtime a year instead of under 9.
Questions people ask
How much downtime is 99.9% uptime?
8 hours 45 minutes 36 seconds a year, 43 minutes 48 seconds a month, about 10 minutes a week, or 86.4 seconds a day.
How much downtime is 99.99% uptime?
About 52.6 minutes a year, or 4 minutes 23 seconds a month.
What uptime is 30 minutes of downtime in a month?
About 99.93%, which misses a 99.95% target but meets 99.9%.