Convert availability percentages to actual downtime.
The "number of nines" has become the standard for measuring service availability. But what does 99.9% vs 99.99% actually mean in terms of allowed downtime minutes?
This calculator helps you understand the real implications of each SLA level. The difference between 99% and 99.9% may seem minimal, but it represents hours of additional downtime per year.
Use this table to define realistic goals and understand what your providers actually promise. A 99.9% SLA means 8.77 hours of downtime per year is considered acceptable.
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| Uptime | seo.calculateur_uptime.col_downtime_day | Downtime/month | Downtime/year |
|---|---|---|---|
| 99% | 14m 24s | 7h 18m | 3j 15h 36m |
| 99.5% | 7m 12s | 3h 39m | 1j 19h 48m |
| 99.9% | 1m 26s | 43m 50s | 8h 45m 57s |
| 99.95% | 43s | 21m 55s | 4h 22m 58s |
| 99.99% | 8.6s | 4m 23s | 52m 35s |
| 99.999% | 0.86s | 26s | 5m 15s |
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Uptime = (Total time - Down time) / Total time × 100. MoniTao automatically calculates this metric for all your monitors.
Depends on your SLA. Some exclude planned maintenance, others don't. Clarify this point with your customers.
Start with 99.9% and measure. Promising more without historical data is risky. You can always increase later.
Multi-region redundancy, automatic failover, canary deployments, dedicated SRE teams. Considerable investments.
No. Even Google services have outages. 100% is mathematically impossible over the long term.
Depending on the contract, penalties or credits may apply. More importantly: your users lose trust.
Understanding the nines helps you set achievable goals and communicate clearly with stakeholders about what's realistically possible.
MoniTao measures your actual uptime and helps you track your progress toward availability goals. Start measuring to improve.
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