Uptime & SLA Calculator
What each uptime percentage actually allows, in time you can picture. Three nines is not "almost perfect".
| Uptime | Per day | Per week | Per month (30d) | Per quarter | Per year |
|---|---|---|---|---|---|
| 99% | 14.4 min | 1.7 hours | 7.2 hours | 21.9 hours | 3.7 days |
| 99.5% | 7.2 min | 50.4 min | 3.6 hours | 11.0 hours | 1.8 days |
| 99.9% | 1.4 min | 10.1 min | 43.2 min | 2.2 hours | 8.8 hours |
| 99.95% | 43.2 s | 5.0 min | 21.6 min | 1.1 hours | 4.4 hours |
| 99.99% | 8.6 s | 1.0 min | 4.3 min | 13.1 min | 52.6 min |
| 99.999% | 864 ms | 6.0 s | 25.9 s | 1.3 min | 5.3 min |
Reading this table
99.9% is the one most people promise, and it allows 43.2 min of downtime a month. That is a long lunch, not a blip — and it is the figure most hosting SLAs quote.
Each extra nine costs ten times more. Going from 99.9% to 99.99% cuts your monthly budget from 43.2 min to 4.3 min. At that point a single slow deploy has spent the month.
Downtime you did not measure still counts. An SLA is only meaningful if something independent is watching — which is the awkward part of grading your own homework.
Knowing the budget is the easy part
Spending it without noticing is the problem. Pingniner measures your real uptime from nine locations and reports it monthly, so the number in your SLA and the number you actually hit are the same number.
Start monitoring free5 monitors free, no card required.
Other free tools: Is it down? · Speed test · Blacklist checker · SSL checker · Cron tester · SPF/DMARC · Redirects · Domain lookup · SLA calculator