Time Duration Calculator
Calculate the elapsed time between a start and end clock time, including across midnight.
Runs 100% in your browser — nothing is uploaded.
Result
Formula
Duration = end − start (modulo 24 h when crossing midnight).
About this calculator
Calculate the elapsed time between a start and end clock time, including across midnight. The calculator converts both times to minutes since midnight, subtracts the start from the end, and adjusts for overnight spans by adding 1440 minutes and taking the remainder modulo 1440.
How to use
- 1
Enter a start and end time in 24-hour format.
- 2
Say whether it crosses midnight.
- 3
Read the duration.
Frequently asked questions
What if I select 'Same day' but my end time is earlier than my start time?
The calculator will return a negative duration, which is not meaningful. For spans that cross midnight, select 'Crosses midnight'.
Can I use AM/PM format?
No, only 24-hour HH:MM format is accepted, e.g., 09:30 for 9:30 AM and 17:45 for 5:45 PM.
Does the calculator account for time zones or daylight saving?
No, it only uses the clock times you enter. It assumes a single time zone and no DST shifts.
Please note: Results are estimates for general information only and are not professional or medical/financial advice.