UPTIME
CALCULATOR
A hosting SLA quoted as 99.9% sounds close to perfect, but it permits nearly 45 minutes of downtime a month. Pick a target or type your own to see the real allowance across every period, then enter an actual outage to see the uptime you achieved and whether the SLA was breached.
Calculated in your browser. An SLA number only matters if the host honours it: HRI scores uptime commitments alongside everything else we can verify.
How HRI scores uptimeWhat is an Uptime Calculator?
An uptime calculator is a free tool that converts an SLA percentage into the downtime it actually permits, per day, week, month, quarter and year. It also works backwards: enter a real outage and it returns the uptime you achieved and whether that breached the target. 99.9% uptime, for example, allows nearly 44 minutes of downtime a month.
How does an Uptime Calculator work?
- 01Choose a common SLA tier or enter any percentage.
- 02We convert it into the downtime permitted per day, week, month, quarter and year.
- 03Enter a real outage in minutes to see the uptime achieved and whether it breached the target.
Frequently asked questions
How much downtime does 99.9% uptime actually allow?
About 43 minutes and 50 seconds a month, or roughly 8 hours 45 minutes a year. Each additional nine cuts that by a factor of ten: 99.99% allows about 4 minutes 23 seconds a month, and 99.999%, the so-called five nines, allows about 26 seconds. The gap between 99.9% and 99.99% is far larger than the numbers suggest.
What do I get if my host breaches its SLA?
Almost always service credits rather than cash, usually a percentage of that month’s fee scaled to how far the breach went. Most agreements also require you to claim within a set window, often 30 days, and credits are rarely applied automatically. Read the remedy clause before assuming a breach is worth anything.
Does scheduled maintenance count against the SLA?
Usually not. Most hosting agreements exclude announced maintenance windows from the uptime calculation, along with outages caused by your own code, third-party networks, or force majeure. This means measured real-world availability is often lower than the SLA figure implies, which is why independent monitoring matters more than the headline number.