Updated November 2026
The short version
- Each extra nine cuts the allowed downtime by about ten times.
- Five nines leaves roughly five minutes a year, measured over a full year.
- What counts as downtime depends on how the SLA defines and measures it.
The nines in minutes
A year has 525,600 minutes. An availability percentage tells you how many of them a service is expected to be up; the rest is the downtime it allows.
- 99%
- Common name: Two nines
- Downtime per year: About 3.65 days
- Downtime per month: About 7.3 hours
- 99.9%
- Common name: Three nines
- Downtime per year: About 8.76 hours
- Downtime per month: About 43.8 minutes
- 99.99%
- Common name: Four nines
- Downtime per year: About 52.6 minutes
- Downtime per month: About 4.4 minutes
- 99.999%
- Common name: Five nines
- Downtime per year: About 5.26 minutes
- Downtime per month: About 26 seconds
These figures are simple arithmetic. How a provider actually measures availability is set out in its SLA.
Why the extra nine matters
The gap between 99.9% and 99.999% looks like a rounding difference, but it is the difference between most of a working day offline each year and a few minutes.
For an office that runs on cloud apps, VoIP calls and video meetings, every minute offline stops work. That is why an SLA, not a best-effort promise, matters when you choose business internet.
What it takes to reach five nines
The last nines are hard because the remaining causes of downtime are the ones a single connection or device cannot solve alone: a cut cable, a power event or failed hardware with no standby.
- Redundancy at each layer that could fail, including the internet connection
- Automatic failover that does not wait for someone to notice
- Testing the failover paths so you know they work
- Monitoring and support that respond at any hour
Keeping your office online
A provider's commitment covers its network, not everything between it and your desk. Pair an SLA-backed main connection with a second path and SD-WAN, which moves traffic to another connection if one has a problem.
5x5 fixed wireless is a primary enterprise connection with built-in redundancy and the same SLA as our fiber, and it can also be the second connection. 5G and 4G LTE add a separate cellular path for backup.
The 5x5 Telecom commitment
For SLA-backed services, we commit to at least 99.999% network availability, subject to the SLA. The SLA also sets latency and packet delivery commitments and the service credits that apply if we miss one.
How availability is measured, what counts as downtime and what is excluded are set out in the SLA itself, so read it alongside this guide.
Related services and guides
What is an SLA?
Commitments, service credits and what to check before you sign.
Service level agreement
Our commitments, credits, claim process and exceptions.
Fixed wireless internet
Primary enterprise internet with the same SLA as our fiber.
Managed SD-WAN
Use several connections together, with automatic failover.