Time Duration Calculator
Calculate the duration between a start time and an end time in total minutes, decimal hours, and hours and minutes.
How It's Calculated
Formula
\text{totalMinutes} = (\text{endHour} \times 60 + \text{endMinute}) - (\text{startHour} \times 60 + \text{startMinute})Time duration is minute arithmetic between two 24-hour clock times, with no calendar date involved. In same-day mode, the end time must be at or after the start time; total minutes is simply the end time's minute-of-day value minus the start time's. In overnight mode, the end time is treated as occurring on the calendar day after the start time: if the end time's minute-of-day value is at or before the start time's, a full day (1,440 minutes) is added before subtracting, so the duration correctly wraps across midnight. The same start and end time in same-day mode yields 0 minutes; it is never interpreted as a full 24 hours. Results are reported three ways: total minutes, decimal hours (minutes / 60), and whole hours plus remaining minutes.
Worked Examples
Same-day duration: 09:15 to 10:45
- Start minute-of-day: 9 x 60 + 15 = 555.
- End minute-of-day: 10 x 60 + 45 = 645.
- Total minutes: 645 - 555 = 90.
- Result: 90 minutes = 1.5 decimal hours = 1 hour 30 minutes.
Overnight duration: 23:00 to 01:00 (overnight enabled)
- Start minute-of-day: 23 x 60 = 1,380.
- End minute-of-day: 1 x 60 = 60.
- End (60) is at or before start (1,380), so add a full day: 60 + 1,440 = 1,500.
- Total minutes: 1,500 - 1,380 = 120.
- Result: 120 minutes = 2 decimal hours = 2 hours 0 minutes.
Frequently Asked Questions
What is the difference between same-day mode and overnight mode?
Same-day mode requires the end time to be at or after the start time and calculates a straightforward same-calendar-day duration. Overnight mode explicitly allows the end time to represent the next calendar day, wrapping the calculation across midnight.
What happens if I enter an earlier end time without enabling overnight?
The calculator reports a validation error instead of silently assuming you meant an overnight duration. Enable the overnight toggle if the end time is really on the next day.
If I enter the same start and end time, is that 0 or 24 hours?
In same-day mode, an identical start and end time is 0 minutes duration. It is never interpreted as a full 24-hour day.
Does this calculator account for dates or time zones?
No. This calculator performs pure clock-time (minute) arithmetic only. For a duration between two specific calendar dates, use the Date Difference Calculator instead.
What time format does this calculator use?
24-hour HH:MM format, entered as separate hour (0-23) and minute (0-59) fields for both the start and end time.