Published: 04.10.2026
Almost every hosting provider promises high availability. A few decimals make a large difference, so it pays to know what the numbers mean.
Downtime per period
- 99%: about 7 hours of downtime a month.
- 99.9%: about 43 minutes a month.
- 99.99%: about 4 minutes a month.
- 99.999%: about 26 seconds a month.
What is an SLA?
A service level agreement is the written commitment of the provider: which availability is guaranteed, how it is measured and what compensation you receive when it is not met, usually service credit.
Read the exclusions
- Planned maintenance is often not counted.
- Problems caused by the customer's software are excluded.
- Network failures outside the provider's control may not count.
- Credit has to be requested within a short time.
How to measure uptime
Use an independent monitoring service that checks your site every minute from several places and alerts you by e-mail or messenger. Check not only the server but also the application: a server can run while the website shows an error.
How to improve your own availability
- Choose a provider with redundant power, network and storage.
- Keep backups and a tested restore plan.
- Remove single points of failure: use several servers behind a load balancer for critical sites.
- Update during low traffic and test changes on a copy.
- Monitor certificates and domain expiry, which cause many outages.
Frequently asked questions
Is 99.9% enough? For most business sites yes. Shops with high turnover may need more.
Does a status page help? Yes. It builds trust and reduces support requests during incidents.
