Uptime Calculator
Enter an uptime or availability percentage.
This result is an estimate only. Double-check important figures before relying on them.
How it is calculated
- Downtime share = 100% − uptime
- Per year = share × 365 days, per month = share × 30 days
- Per week and per day follow in the same way
To work with other time units, use the time units converter.
Worked example
99.9% uptime:
- Per year: 8 h 45 min 36 s
- Per month: 43 min 12 s
Why your number may differ
A month is taken as 30 days and a year as 365. Real SLAs may measure over a calendar month or use different rules.
Frequently asked questions
What does 99.9% uptime mean?
The service can be down for 0.1% of the time. Over a year that is about 8 hours 45 minutes.
What are “the nines”?
Shorthand for uptime: three nines is 99.9%, four nines is 99.99% and five nines is 99.999%. Each extra nine cuts allowed downtime by a factor of ten.
Does it include planned maintenance?
It depends on the agreement. Many SLAs exclude scheduled maintenance, so read the contract.