Uptime and SLA calculator
Enter an uptime target to see how much downtime it allows each day, week, month, quarter and year. Or start from minutes of downtime and get the percentage.
Runs in your browser: nothing is sent anywhere.
OwlHound measures your real uptime every 5 minutes and gives you a monthly SLA report to print or share.
Monitor this automaticallyWhat this check means
An uptime percentage is the share of time a site is reachable. Hosts and SLAs promise a figure such as 99.9%, and the gap between figures is easier to judge in minutes: each extra nine cuts the allowed downtime by ten. The calculator uses a 30.44-day month and a 365.25-day year, the averages most SLAs use.
Frequently asked questions
How much downtime does 99.9% allow?
About 43 minutes 50 seconds a month, or 8 hours 46 minutes a year. 99.99% allows about 4 minutes 23 seconds a month.
What uptime should a small business site aim for?
99.9% is a sensible target on decent hosting. 99.99% usually needs redundant servers, which most small sites don't need.
Does planned maintenance count as downtime?
It depends on the agreement: many SLAs exclude announced maintenance windows. For your visitors, though, a site under maintenance is down either way.