SLA math
99.999% uptime: five nines is ~5 minutes a year
Five nines is a telephony-era slogan. Most product teams should not print it unless the architecture and staffing already match.
Target
99.999%
Allowed downtime / year
5 minutes / year
Per month (avg)
0.4 minutes
Who uses it
Who usually picks 99.999%
Rare outside regulated or carrier-grade systems. Prefer honest three or four nines plus transparent status history.
Caveats
Read this before you print it on a sales slide
- A single bad deploy can spend the yearly budget
- Measuring five nines requires probes and process most startups do not have
- Customers prefer truthful 99.9% + great communication over fictional five nines
FAQ
99.999% uptime, answered
Exact minutes for five nines, why most SaaS should not promise it, and what to publish instead.
Keep reading
Related SLA and cost tools
- What counts as good uptime
99.9% vs 99.99% vs 99.999% in plain English.
- How to write an uptime SLA
Promises you can actually keep.
- Downtime cost calculator
Turn outage minutes into dollars.
- 99.9% uptime
8.8 hours / year
- 99.95% uptime
4.4 hours / year
- 99.99% uptime
53 minutes / year
Defend 99.999% with clearer pages
False pages waste the people who keep a 99.999% promise. Tallwatch opens incidents when at least two regions agree — Free includes consensus.