The Math Behind Uptime Percentages
Every web host advertises an uptime guarantee. These numbers feel impressive until you convert them to actual downtime:
- 99% uptime — 87.6 hours of downtime per year. Over 3.5 days offline.
- 99.9% uptime — 8.76 hours of downtime per year.
- 99.95% uptime — 4.38 hours of downtime per year.
- 99.99% uptime — 52.6 minutes of downtime per year.
For most websites the difference between 99.9% and 99.99% is not meaningful. For an e-commerce store generating $10,000 per hour, it is a significant financial calculation.
What Counts as Downtime?
Most hosting uptime guarantees define downtime as total inaccessibility — meaning 100% of requests fail. A server responding slowly or timing out intermittently may not count as downtime under the SLA. In practice, a site that takes 15 seconds to load is effectively down for your visitors. This is why independent monitoring matters more than host-provided uptime statistics.
How to Monitor Your Own Uptime
UptimeRobot (Free) — Checks your site every 5 minutes from external servers and sends email or SMS alerts. Free tier monitors up to 50 sites.
Pingdom (from $10/month) — One-minute check intervals and multiple locations. Worth it for revenue-generating sites.
Better Uptime (Free tier) — Incident management with Slack integration. Good for development teams.
Our 12-Month Uptime Data
We monitor test sites on major hosts continuously. Over 12 months these were our results:
- Hostinger: 99.97% — approximately 2.6 hours total downtime
- SiteGround: 99.98% — approximately 1.75 hours total downtime
- Cloudways: 99.99% — approximately 52 minutes total downtime
- Bluehost: 99.91% — approximately 7.9 hours total downtime
The industry average across all hosts we tested was 99.93%. Anything below 99.9% in real-world testing should be considered unacceptable for a production website.
