Uptime / SLA Calculator
A free, browser-based calculator. Runs entirely in your browser — no sign up, nothing stored.
100% FreeRuns in your browserBasic
Enter Values
Enter your values and press Calculate to see results.
How to use this calculator
- Enter the uptime percentage (e.g. 99.9).
- Press Calculate for the allowed downtime.
How it works
Downtime is the time the service is allowed to be unavailable: (1 − uptime%) of the period. Each extra '9' cuts the downtime roughly tenfold.
Worked example
99.9% uptime. About 526 minutes (8.8 hours) of downtime a year.
Related tools
Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.