Tech calculator
Uptime Calculator
See the downtime budget behind an availability target.
Average monthly downtime
43m 50s
How the uptime calculator works
Convert an uptime percentage into allowed downtime per day, month, and year.
99.9% uptime permits about 43 minutes 50 seconds of downtime in a 30.4375-day average month.
Assumptions and limitations
Months use the annual average of 365.25 ÷ 12 days. Maintenance windows count unless your service agreement excludes them.
Inputs and results stay in your browser. Blank, invalid, or mathematically undefined inputs show a clean placeholder instead of a broken number.
Practical use
Use this tech calculator to explore scenarios quickly, then verify important decisions against the original source data or requirements.
Frequently asked questions
Does the uptime calculator send my data anywhere?
No. It runs client-side in your browser and makes no network requests.
Why is the result blank or shown as a dash?
One or more inputs are blank, outside the accepted range, or would make the calculation undefined. Check the labels and enter finite values.
Can I use decimal values?
Yes, where decimals are meaningful. Counts that represent whole items may require integers.