Time Duration Calculator
Compare two local clock times and choose whether an earlier end wraps to the next day or remains a negative duration.
A QUICK WALKTHROUGH
How to use this tool
- Enter the start and end clock times.
- Choose overnight wrap for a span crossing midnight, or signed duration to preserve a negative result.
- Calculate and review the duration in hours and minutes.
Two clear interpretations
Overnight wrap treats an end time earlier than the start as the following day. Signed duration keeps the direct subtraction, so the same example is −21 hours 15 minutes.
Clock times only
This calculator accepts local 24-hour clock times and performs the calculation in your browser. It does not use dates, time zones, daylight-saving rules, or eval.
GOOD TO KNOW
Common questions
What happens when the times are equal?
The duration is zero in either mode.
Can I calculate an overnight span?
Yes. Choose Overnight wrap when the end clock time is earlier than the start.
Why use signed duration?
It makes the direction explicit when you want end minus start without wrapping to another day.