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About the Time Duration Calculator
The time duration calculator measures the elapsed time between two clock times. It answers the question “how long did it take?” with an exact figure in hours, minutes and seconds.
Both time boxes accept hours, minutes and seconds. The “Now” link under each box fills it with the current time from your device, which is useful for timing something that is happening right now. The “End is this many days later” box handles spans longer than one day.
When the end time is earlier than the start time and no extra days are set, the calculator rolls the end time into the next day. The result shows the duration in words, clock format (h:mm:ss), decimal hours, total minutes and total seconds.
How to Use the Time Duration Calculator
- Enter the start time, or press “Now” to use the current time.
- Enter the end time, or press “Now”.
- If the end falls one or more days after the start, enter the number of days.
- Read the elapsed time in the result panel.
How to Calculate Time Between Two Times
Converting both times to minutes or seconds makes the math simple.
- Write both times in 24 hour format.
- Convert each time to minutes after midnight: hours × 60 + minutes.
- Subtract the start from the end.
- If the result is negative, add 1,440 minutes (one day).
- Divide by 60. The whole number is hours and the remainder is minutes.
8:15 = 8 × 60 + 15 = 495 minutes
17:45 = 17 × 60 + 45 = 1,065 minutes
1,065 − 495 = 570 minutes
570 ÷ 60 = 9 hours 30 minutes
To include seconds, work in seconds instead. A day has 86,400 seconds.
Time Duration Examples
| Start | End | Duration | Total minutes | Decimal hours |
|---|---|---|---|---|
| 6:00 AM | 2:30 PM | 8 h 30 min | 510 | 8.50 |
| 8:15 AM | 5:45 PM | 9 h 30 min | 570 | 9.50 |
| 9:40 AM | 1:05 PM | 3 h 25 min | 205 | 3.42 |
| 11:30 AM | 11:30 PM | 12 h | 720 | 12.00 |
| 1:20 PM | 4:55 PM | 3 h 35 min | 215 | 3.58 |
| 3:10 AM | 9:40 PM | 18 h 30 min | 1,110 | 18.50 |
| 7:45 PM | 6:15 AM (next day) | 10 h 30 min | 630 | 10.50 |
| 10:00 PM | 2:30 AM (next day) | 4 h 30 min | 270 | 4.50 |
| 11:55 PM | 12:20 AM (next day) | 25 min | 25 | 0.42 |
| 4:00 PM | 3:59 PM (next day) | 23 h 59 min | 1,439 | 23.98 |
Duration Across Midnight and Multiple Days
Across midnight: if the end time is earlier on the clock than the start time, the span runs through midnight. 10:00 PM to 2:30 AM is 4 hours 30 minutes. 4:00 PM to 3:59 PM is 23 hours 59 minutes.
Multiple days: each extra day adds 24 hours. From 6:00 AM to 9:00 AM two days later is 48 + 3 = 51 hours. Set “End is this many days later” to 2 to get this result.
Duration and Daylight Saving Time
The calculator measures clock to clock. On the nights clocks change, the real elapsed time differs by one hour. In the United States, daylight saving time starts at 2:00 AM on the second Sunday in March and ends at 2:00 AM on the first Sunday in November, as set by the Energy Policy Act of 2005. A 10:00 PM to 6:00 AM shift lasts 7 real hours in March and 9 real hours in November. Adjust by one hour for spans that cross the change.
Duration Versus Clock Time
A clock time names a moment, such as 3:15 PM. A duration measures the length between two moments, such as 2 hours 40 minutes. Clock times reset every 24 hours. Durations do not, so a duration can be 26 hours long. This calculator always returns a duration. To find the clock time after adding a duration, use the “Add time to a clock time” mode of the time calculator.
Frequently Asked Questions
What is a time duration calculator?
A time duration calculator is a tool that finds the length of time between a start time and an end time. It returns the elapsed time in hours, minutes and seconds, and often in decimal hours as well.
What is elapsed time?
Elapsed time is the amount of time that passes between a start and an end. For example, the elapsed time from 9:20 AM to 11:05 AM is 1 hour 45 minutes.
How do I calculate the time between two times?
Convert both times to minutes after midnight, subtract the start from the end, and add 1,440 if the result is negative. Divide by 60 to get hours, and the remainder is minutes.
How do I find the duration when the end time is past midnight?
Add 24 hours to the end time before subtracting. From 10:00 PM to 2:30 AM, treat 2:30 as 26:30. Then 26:30 minus 22:00 equals 4 hours 30 minutes.
Can the duration calculator include seconds?
Yes. Both time boxes accept seconds, and the result includes total seconds along with hours and minutes.
How do I calculate a duration longer than 24 hours?
Enter the number of days between the start and the end in the “End is this many days later” box. The calculator adds 24 hours for each day.
What is the difference between duration and time difference?
Duration is the time between two moments in one place. Time difference usually means the gap between two time zones. For time zones, use the time difference calculator.