Time Duration Calculator

Free Online Time Duration Calculator

Our Time Duration Calculator helps you find the exact time difference between two times of the day. Whether you are tracking work hours, calculating travel time, or measuring event durations, this tool provides instant results in hours, minutes, seconds, and HH:MM:SS format. Simply enter your start and end times with AM/PM selection and get the precise duration. For conversions, try our Time Converter and Time Calculator.

How to Calculate Time Duration

Calculating the duration between two times involves converting both times to a 24-hour format, finding the difference in seconds, and then converting back to hours, minutes, and seconds.

Formula:

Convert both times to 24-hour format (add 12 to PM hours, except 12 PM which stays 12)
Duration (seconds) = End Time (seconds) - Start Time (seconds)
If the result is negative, add 24 hours (86,400 seconds) to account for overnight duration
Hours = Total Seconds ÷ 3600
Minutes = Total Seconds ÷ 60

Example Calculations

Start Time	End Time	Duration
9:00 AM	5:00 PM	8 hours 0 minutes
8:30 AM	4:45 PM	8 hours 15 minutes
10:00 PM	6:00 AM	8 hours 0 minutes (overnight)
12:00 PM (Noon)	1:00 PM	1 hour 0 minutes
11:30 PM	1:15 AM	1 hour 45 minutes (overnight)

Common Use Cases

Work Hours Tracking: Calculate the exact hours you worked in a day.
Travel Planning: Measure the duration of flights, road trips, or commutes.
Event Planning: Determine how long meetings, events, or appointments last.
Project Management: Track time spent on tasks and activities.
Shift Scheduling: Calculate shift lengths for employees across different time periods.

Understanding AM and PM

The 12-hour clock divides the day into two periods: AM (Ante Meridiem, meaning "before noon") from midnight to noon, and PM (Post Meridiem, meaning "after noon") from noon to midnight. When calculating durations across the AM/PM boundary, the calculator automatically handles the overnight transition by adding 24 hours when the end time is earlier than the start time.

Frequently Asked Questions

How do I calculate the time between two times?

Convert both times to 24-hour format, calculate the difference in seconds, and convert to hours and minutes. If the end time is earlier than the start time (e.g., 10 PM to 6 AM), it means the duration crosses midnight and 24 hours should be added.

How many hours is 9 AM to 5 PM?

9:00 AM to 5:00 PM is exactly 8 hours. This is a standard full-time work day in many countries, often referred to as a "9-to-5" job.

Does this calculator handle overnight durations?

Yes. If your end time is earlier than your start time (e.g., starting at 10:00 PM and ending at 6:00 AM), the calculator automatically detects the overnight transition and adds 24 hours to give you the correct duration of 8 hours.

Can I calculate duration in just hours or minutes?

Yes. The calculator shows the duration in multiple formats simultaneously: HH:MM:SS format, total hours with decimals, total minutes with decimals, and total seconds. Choose whichever format is most useful for your purpose.

What is the difference between 12 AM and 12 PM?

12 AM is midnight (the start of the day), while 12 PM is noon (the middle of the day). 12:00 AM is 00:00 in 24-hour format, and 12:00 PM is 12:00 in 24-hour format.

Is this calculator useful for payroll?

Yes, this calculator is useful for estimating work hours. However, for official payroll purposes, you should use a dedicated time card calculator that accounts for lunch breaks, overtime rules, and rounding policies as required by labor laws.

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