SLA Uptime Calculator
| Period | Minutes | Readable |
|---|---|---|
| Day | 1.440 | 1.44 min |
| Week | 10.080 | 10.08 min |
| Month | 43.834 | 43.83 min |
| Quarter | 131.486 | 2.19 h |
| Year | 525.960 | 8.77 h |
Standard SLA comparison
| Level | SLA | Name | Downtime/year |
|---|---|---|---|
| Basic | 99% | Two 9s | 3,65 giorni |
| Standard | 99.5% | Three-half 9s | 1,83 giorni |
| High selected | 99.9% | Three 9s | 8,77 ore |
| Very High | 99.95% | Three-and-half 9s | 4,38 ore |
| Carrier Grade | 99.99% | Four 9s | 52,6 min |
| Five Nines | 99.999% | Five 9s | 5,26 min |
Frequently Asked Questions
Everything you need to know about uptime SLAs
What is an SLA (Service Level Agreement)?
An SLA is a contractual agreement that defines the expected level of service from a provider. In the IT context, the uptime SLA indicates the percentage of time the service must be available. A 99.9% SLA means the service can have at most 8.76 hours of downtime per year.
What does "four 9s" or "five 9s" mean?
"Four 9s" is jargon for 99.99% uptime, corresponding to about 52 minutes of annual downtime. "Five 9s" (99.999%) is the standard for mission-critical systems like telephone networks, equivalent to about 5 minutes of annual downtime. Each additional "9" reduces downtime by about 10 times.
How is allowed downtime calculated?
The calculation is simple: downtime = (1 - SLA%) × period. For example for 99.9%: (100% - 99.9%) × 525,600 minutes/year = 525.6 minutes/year ≈ 8.76 hours. This tool automatically calculates for day, week, month, quarter and year.
What SLA should I require from my cloud provider?
It depends on the type of service: for corporate websites 99.9% is sufficient, for business-critical applications 99.95%-99.99% is recommended, for financial or healthcare infrastructures at least 99.99%-99.999% is required. Also consider the contractual penalties in case of SLA violation.
What is an uptime SLA?
It is the contractual commitment on the share of time a service has to be reachable. A commitment at 99.9 per cent leaves about eight hours and forty minutes of downtime in a year.
What do four nines or five nines mean?
They are ways of saying 99.99 and 99.999 per cent: the first leaves about fifty-two minutes of downtime a year, the second about five. Every extra nine divides the allowed time by ten.
How is the allowed time worked out?
By multiplying the part missing from a hundred per cent by the length of the period. For 99.9 per cent over a year you take 0.1 per cent of 525,600 minutes, which is about 526 minutes.