SLA Uptime Calculator
Enter an uptime percentage and see how much downtime it actually allows per day, week, month, and year. Or flip it: enter the downtime you had and find out what percentage you hit.
Reverse: downtime to uptime %
Had an incident and need to report the resulting uptime? Enter total downtime and the period it occurred in.
Downtime allowed at each level of nines
The standard tiers, precomputed. A 30-day month is used because that's what most SLAs and monitoring tools measure against, not the calendar month.
| Uptime | Per day | Per week | Per month (30d) | Per year |
|---|---|---|---|---|
| 99% | 14m 24s | 1h 40m 48s | 7h 12m | 3d 15h 36m |
| 99.5% | 7m 12s | 50m 24s | 3h 36m | 1d 19h 48m |
| 99.9% | 1m 26s | 10m 5s | 43m 12s | 8h 45m 36s |
| 99.95% | 43s | 5m 2s | 21m 36s | 4h 22m 48s |
| 99.99% | 8.6s | 1m 0s | 4m 19s | 52m 34s |
| 99.999% | 0.9s | 6s | 26s | 5m 15s |
Notes worth knowing
An SLA number on its own says nothing about incident shape. 43 minutes per month at 99.9% could be one painful outage or thirty short blips, and your users experience those very differently. Detection time eats into the budget too; if your monitoring checks every 5 minutes, you can lose up to 5 minutes of budget before anyone even knows.
Watch the measurement window in vendor SLAs. Some compute uptime per calendar month, some per billing cycle, and a few measure per year, which lets a vendor burn the entire annual allowance in one incident while technically staying compliant.
Related tools
- Error Budget Calculator: track how much of this allowance you've already spent.
- Downtime Cost Calculator: what those minutes cost in money.
Knowing the budget is step one. Catching the burn is step two.
failover.io checks your endpoints as often as every 15 seconds and escalates alerts from email to SMS to a phone call until a human acknowledges. The free plan monitors 5 endpoints at 60-second intervals, no card required.
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