How long was the flight, the shift, the drive or the exam? This time duration calculator measures the elapsed time between two clock times, or between two full date-and-time points, and reports it in hours and minutes, decimal hours, minutes and seconds. Spans that cross midnight are handled automatically, and date-time spans can be adjusted for US daylight saving time changes.
How to use the time duration calculator
- Choose Two clock times for spans of less than a day, or Two dates and times for anything longer.
- Enter the start and end. With clock times, an end earlier than the start is read as the next day.
- In date-time mode, leave Adjust for US daylight saving time ticked if the times are local clock times in a US zone that changes its clocks.
- Read the duration in words, h:mm, decimal hours and total minutes.
How elapsed time is calculated
Clock times are converted to minutes after midnight and subtracted:
For dates and times, both points are converted to a continuous count of seconds and subtracted. With the daylight saving option on, each clock change between them is applied:
Worked examples
A workday: 9:15 AM to 5:40 PM is 1,060 − 555 = 505 minutes = 8 hours 25 minutes, or 8.4167 decimal hours.
A night shift: 10:00 PM to 6:30 AM. The end is earlier, so add a day: 1,830 − 1,320 = 510 minutes = 8 hours 30 minutes.
Across spring forward: Saturday, March 7, 2026 at 10:00 PM to Monday, March 9 at 6:30 AM reads as 32 hours 30 minutes on the clock. Clocks sprang forward at 2:00 a.m. on Sunday, March 8, so the time that actually passed is 31 hours 30 minutes.
Across fall back: 8:00 PM on Saturday, October 31, 2026 to 8:00 AM the next morning looks like 12 hours, but the 1 a.m. hour repeats on November 1, so 13 hours actually pass. A night-shift worker on that date works an extra hour.
US daylight saving time dates
| Year | Clocks spring forward | Clocks fall back |
|---|---|---|
| 2026 | Sunday, March 8 | Sunday, November 1 |
| 2027 | Sunday, March 14 | Sunday, November 7 |
| 2028 | Sunday, March 12 | Sunday, November 5 |
The current schedule was set by the Energy Policy Act of 2005 and took effect in 2007. From 1987 through 2006, DST ran from the first Sunday in April to the last Sunday in October; the calculator knows those older rules too, back to 1967. Hawaii and most of Arizona do not observe daylight saving time, nor do Puerto Rico, Guam and the other US territories, so untick the option for times there.
Clock-time pitfalls
- AM and PM: 12:00 AM is midnight and 12:00 PM is noon. Mixing them up makes a 1-hour lunch look like 13 hours.
- Nonexistent and repeated times: 2:30 a.m. does not exist on the spring-forward date, and 1:30 a.m. happens twice on the fall-back date. Log those times with a time zone abbreviation (EST or EDT) to avoid disputes.
- Payroll: for shifts with unpaid breaks, overtime and pay, use the hours calculator or the time clock calculator.
To find the clock time a set number of hours after a start time, use the add time calculator; for whole days between dates, the date difference calculator.
Frequently asked questions
How many hours are between 9:15 AM and 5:40 PM?
8 hours 25 minutes. In minutes after midnight the times are 555 and 1,060, and 1,060 − 555 = 505 minutes, which is 8:25 or 8.4167 decimal hours.
How do I calculate time across midnight?
If the end time is earlier than the start, add 24 hours to the end before subtracting. From 10:00 PM to 6:30 AM is (6:30 + 24:00) − 22:00 = 8 hours 30 minutes. The calculator does this automatically.
How does daylight saving time change the result?
On the spring-forward night clocks jump from 2:00 to 3:00 a.m., so a span across it is one hour shorter than the clock times suggest. On the fall-back night 1:00 to 2:00 a.m. happens twice, so the span is an hour longer.
What are the US daylight saving dates?
Since 2007 daylight saving time starts on the second Sunday in March and ends on the first Sunday in November, both at 2:00 a.m. local time. In 2026 that is March 8 and November 1.
What if I need durations longer than a day?
Switch to Two dates and times. The result is shown in days, hours and minutes, and as total hours, minutes and seconds.