# Uptime calculator

Convert an uptime percentage into allowed downtime for 24 hours, 30 days, a year, or a custom window. Runs in your browser.

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.
Network access: no
Stores input: no
Client-side only: yes
Canonical: https://fajita.io/tools/uptime-calculator

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