Uptime and downtime with 99.9 % SLA

2025-11-27:

It's always DNS. I built uptime mongers to monitor the DNS security issues that standard services ignore: parent zone delegation changes, stale DNSSEC signatures, expired RRSIGs. Get alerted when nameservers change at your registrar without your permission.

SLA & Uptime Calculator

How much downtime corresponds to your SLA?

%

(enter SLA level and hit the <enter> key)

SLA level of 99.9 % uptime/availability results in the following periods of allowed downtime/unavailability:

Daily
1m 26s
Weekly
10m 4.8s
Monthly
43m 50s
Quarterly
2h 11m 29s
Yearly
8h 45m 57s

Direct link to the page with these results: uptime.is/99.9 uptime.is/three-nines

The SLA calculations assume a requirement of continuous uptime (i.e. 24/7 all year long) with additional approximations as described in the source. uptime.is was originally implemented in newLISP, which had powered uptime and downtime calculations for more than a decade.

For convenience, there are special CEO and SEO friendly links for N nines:

three nines, four nines, five nines, six nines etc.