Uptime calculator
Convert an uptime percentage into allowed downtime for 24 hours, 30 days, a year, or a custom window. Runs in your browser.
Allowed downtime over 30 days: 43 minutes 12 seconds
Available time: 29 days 23 hours 16 minutes 48 seconds
Calendar months vary in length. The 30-day option uses exactly 30 days. Uptime percentage is not automatically contractual SLA compliance.
| Target | Allowed downtime |
|---|---|
| 99% | 7 hours 12 minutes |
| 99.9% | 43 minutes 12 seconds |
| 99.99% | 4 minutes 19 seconds |
| 99.999% | 25.92 seconds |
Input privacy
All inputs stay in your browser. No server request is made. Nothing is stored. Analytics events never include your percentage or custom duration.
Methodology
Allowed downtime equals (1 - uptime/100) multiplied by the selected period in seconds. Available time equals uptime/100 multiplied by the period. Calendar months vary; the 30-day option uses exactly 30 days.
Enter a target uptime percentage and a time window. The calculator returns allowed downtime and available time. It does not claim SLA compliance.
Methodology
Allowed downtime = (1 - U) × T, where U is the uptime fraction and T is the period length. See How to Calculate Uptime Correctly.
Limitations
- Check intervals limit how precisely downtime can be known
- Maintenance treatment changes the meaning of the percentage
- This tool does not replace monitoring
Limitations
- Does not equal contractual SLA compliance by itself
- Does not model maintenance exclusions unless you adjust the window
- Monitoring definitions of downtime vary by product
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