Uptime Downtime Budget Calculator
Allowed downtime equals the monitoring window multiplied by one minus the uptime target. A 99.9% target over 30 days allows 43.2 minutes in this time-based model.
Formula & method
Downtime seconds = days × 86,400 × (1 − uptime percentage ÷ 100).Worked example
| Input | Value |
|---|---|
| Window length | 30 d |
| Target availability | 99.9 % |
| Result | Value |
|---|---|
| Allowed downtime | 43.2 min |
| Allowed downtime | 2,592 s |
Compare scenarios
The first input changes while the other example inputs stay fixed. These are arithmetic scenarios, not forecasts.
| Compare scenarios | Window length d | Allowed downtime | Allowed downtime |
|---|---|---|---|
| −20% | 24 | 34.56 min | 2,073.6 s |
| Example | 30 | 43.2 min | 2,592 s |
| +20% | 36 | 51.84 min | 3,110.4 s |
Assumptions & limits
This is a time-based arithmetic budget, not an interpretation of any hosting SLA. Some services measure successful requests instead, exclude planned maintenance, or use specific billing windows. A 30-day model is not every calendar month.
Displayed results are rounded. Calculations use unrounded JavaScript numbers; small floating-point differences are possible.
Works in your browser
The interactive tool runs in a sandbox with network access blocked. ClearByte and the advertising scripts cannot read values inside it. Browser extensions and a compromised device remain outside this protection.
Sources & definitions
Method checked:
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