Every host claims 99.9% uptime. Here is what the number really means and how to separate serious providers from marketers.
The arithmetic of the nines - 99% = up to 7.2 hours down per month - 99.9% = up to 43 minutes per month - 99.99% = up to 4.3 minutes per month
Each extra '9' costs real infrastructure money — that is why the jump from 99.9 to 99.99 usually means a different (pricier) product tier.
What the guarantee usually excludes Read the fine print: most SLAs exclude scheduled maintenance, your own application errors, and sometimes 'network issues beyond our control'. The guarantee is a compensation formula (often hosting credit), not magic.
Questions that reveal the truth 1. Where is status published, and how quickly during incidents? 2. What was actual uptime last quarter? (Serious hosts track it) 3. What happens to my data during an outage — and what is the RTO (recovery time)? 4. Is support staffed during the outage, or does everyone wait for the same queue?
What matters more than the number For a small business site, the difference between 99.9 and 99.95 is invisible. What IS visible: how fast support responds when something breaks, whether backups restore cleanly, and whether you hear about problems from the host before customers tell you.
Kairalmas runs monitored NVMe servers with published status, and when something affects you, the answer arrives on WhatsApp — which is the part customers actually remember.