Calculate downtime
Enter a target from 0 to 100% and a reporting period greater than zero. A day means exactly 86,400 seconds. Use 30 days for a 30-day month or 365 days for a 365-day year.
Result
Enter your inputs and run the tool.
Networking
Uptime and Downtime Calculator
Choose an availability percentage and an exact period length. Get a downtime allowance in seconds without signing up or connecting a monitoring service.
Method and assumptions
Allowed downtime = period in days × 86,400 × (100 − availability) ÷ 100. Required uptime is the remaining time in that period.
Worked examples
99.9% over one day
The allowance is 86.4 seconds of downtime; required uptime is 86,313.6 seconds.
99.9% over 30 days
The allowance is 2,592 seconds, or 43 minutes 12 seconds. A 100% target allows zero downtime; 0% allows the whole period.
Limits and useful checks
This is an arithmetic allowance, not live monitoring or an interpretation of an SLA contract. Reporting periods, excluded incidents, rounding and service-credit rules may differ. The default month is exactly 30 days, not an average calendar month.
For mistakes or suggestions, contact UtilTrove. Please include a non-sensitive example.