How this calculation works
Add or subtract clock times and durations across midnight. The result is calculated locally in your browser from the visible inputs, and the method below remains available for checking.
Worked example
Adding 2 hours to 23:30 produces 01:30 the following day.
Assumptions and limits
- Inputs use the units shown beside each field.
- Intermediate values retain precision; displayed values are rounded for readability.
Questions people ask
How does the Time Calculator work?
It applies this displayed method: Signed duration seconds are added to the starting clock time and normalised into a 24-hour day plus day offset. Values stay in your browser and are not submitted to a server.
What should I check before using the Time result?
Inputs use the units shown beside each field. Intermediate values retain precision; displayed values are rounded for readability. Calendar and time-zone results use browser date and IANA timezone data; legal deadlines may follow jurisdiction-specific rules.
Does this Time calculator save my information?
No. Calculation inputs are processed on this device. Sharing creates a URL only when you choose the share action.