Time Duration Calculator

Find the exact time difference between two times or between two dates and times. It can display results in days, hours, minutes, and seconds.

Time Between Two Times

Use this calculator to measure the elapsed time between two clock times. It supports both 12-hour (AM/PM) and 24-hour formats. If the end time is earlier than the start time, the calculation is treated as crossing midnight.

Example:

If the start time is 9:15:30 AM and the end time is 2:45:10 PM, the time difference is 5 hours, 29 minutes, and 40 seconds.

If the start time is 11:30:00 PM and the end time is 1:15:00 AM, the result is 1 hour and 45 minutes.

Time Between Two Dates and Times

Use this calculator to find the exact duration between two complete date-and-time values. It accounts for actual calendar dates, month lengths, and leap years.

Example:

From Jan. 15, 2024, 10:00:00 AM to Jan. 18, 2024, 3:30:00 PM, the elapsed time is 3 days, 5 hours, and 30 minutes.

Leap year example: from Feb. 28, 2024, 12:00:00 PM to Mar. 1, 2024, 12:00:00 PM, the result is 2 days.

How to Calculate Time Difference

To calculate the time between two times, convert each time into total seconds and subtract the start value from the end value. For a negative result, add 86,400 seconds to represent a next-day difference. For date-and-time calculations, subtract the start timestamp from the end timestamp.

Formulas Used

Total Seconds = (Hours × 3600) + (Minutes × 60) + Seconds

Time Difference = End − Start

If Difference < 0, then Difference = Difference + 86,400

Hours = floor(Total Seconds ÷ 3600)

Minutes = floor((Total Seconds mod 3600) ÷ 60)

Seconds = Total Seconds mod 60

A leap year is any year divisible by 4, except for years divisible by 100, unless they are also divisible by 400.

FAQ

Does this calculator handle leap years?

Yes. The date-and-time calculator automatically handles leap years.

Does the time-only calculator work across midnight?

Yes. If the end time is earlier than the start time, it is treated as the next day.

Can I use both 12-hour and 24-hour formats?

Yes. Both formats are supported.

References

• NIST Time and Frequency Division: https://www.nist.gov/pml/time-and-frequency-division
• NIST Daylight Saving Time Resources: https://www.nist.gov/pml/time-and-frequency-division/popular-links/daylight-saving-time-dst
• U.S. Naval Observatory: https://www.usno.navy.mil/