SLA and uptime calculator
Availability percentages sound abstract. Here you see how much downtime hides behind 99, 99.9 or 99.99 percent, and what your downtime minutes mean in percent.
- per day
- 1.4 min
- per week
- 10.1 min
- per month
- 43.2 min
- per year
- 8.8 h
That is how much downtime this promise allows on paper.
The other way round: measured downtime in minutes
That equals an availability of
99.900 %
| Availability | per day | per month | per year |
|---|---|---|---|
| 99 % | 14.4 min | 7.2 h | 3.7 days |
| 99.5 % | 7.2 min | 3.6 h | 1.8 days |
| 99.9 % | 1.4 min | 43.2 min | 8.8 h |
| 99.95 % | 43 s | 21.6 min | 4.4 h |
| 99.99 % | 9 s | 4.3 min | 52.6 min |
| 99.999 % | 1 s | 26 s | 5.3 min |
Pure conversion, not a measurement. What your provider actually delivered can only be shown by your own recording.
The common tiers in plain terms
Every extra nine costs roughly ten times the effort and cuts the allowed downtime to a tenth. That is why the jump from 99.9 to 99.99 percent is expensive and unnecessary for most websites.
What really matters in an SLA
- Reference period: 99.9 percent per month allows far less in one go than 99.9 percent per year.
- What counts as downtime: planned maintenance is often excluded.
- Who measures: without independent recording the promise is hard to verify.
- What happens on a breach: usually a credit that rarely covers the damage.
Frequently asked questions
Why is 99.9 percent not that much?
Because it allows around 43 minutes of downtime per month, in one go. For a shop that can be a noticeable loss.
Do I need my own measurement for an SLA?
For your own peace of mind, yes. An independent history shows what actually happened, regardless of the provider status page.
Checking once is good. Monitoring continuously is better: three monitors are free.
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