# ⏱ Time Duration Calculator + Add & Subtract

Welcome to the world of time calculation, a vital tool for your daily planning and scheduling needs. Whether you want to determine the duration between two times, say 8:00am and 6:45pm (which gives you 10 hours and 45 minutes), or need to calculate work hours for payroll, our time calculator makes it a breeze. However, if you prefer a bit of mathematical challenge, manual computation is always an option.

## Time Between Two Times

Our time duration calculator provides a simple and intuitive interface to compute the time between two times. Just input your start and end times, and the tool will instantly provide the duration in hours, minutes, and seconds.

## Time Difference: Time and Date Calculator

This tool allows you to calculate the precise difference between two time points, down to the second, or between two dates, accounting for months and years.

## Time Addition & Subtraction Calculator

Our versatile calculator also allows you to add or subtract time effortlessly. This feature is particularly useful when planning for future events or determining the span between two points in time. Just choose the operation you wish to perform—addition or subtraction—and let the calculator handle the rest.

Operating our Time Addition & Subtraction Calculator is straightforward. Simply enter a start time in days, hours, minutes, or even seconds. Then, choose the operation (addition or subtraction) and input the end time. The calculator will then automatically generate the time difference or sum between the two inputs, providing the results in days, hours, minutes, and seconds.

## Calculating Time Difference Manually

For those who enjoy manual computations, here are the steps to calculate time difference manually:

1. Convert the time to a 24-hour format. This may require adding 12 to PM hours.
2. Convert all end times from hours to minutes. If the start minutes are higher than the end minutes, subtract one hour from the end hours and add 60 minutes to the end minutes.
3. Subtract the start time minutes from the end minutes.
4. Perform the same subtraction operation for the hours.
5. Finally, combine the hours and minutes results to get the answer.

## Tips to calculate easily

The easiest way to tell the time difference between two times is to use the online calculator. It is faster and more convenient. By inputting the start time and end time, you can also compute the results with up to the last minutes and seconds in one click.

But for those that want to do manual computation, it is important to make sure that your times follows the same format.

## Common units of time

Time, like other numbers, can be added or subtracted. There’s also common units of time that everyone is familiar with, which is used to refer to a particular set of time.

Unit of TimeWhat it means
millenium1,000 years
century100 years
year365.242 days or 12 months
leap year366 days or 12 months
quarter3 months
month28-31 days depending on the month
week7 days
day24 hours or 1,440 minutes
or 86,400 seconds
hour60 minutes or 3,600 seconds
minute60 seconds
secondbase unit of time

## Did you know?

• One of the earliest proponents of the concept of time is Greek philosopher Aristotle, who defined time back then as a “number of movements in respect of the before and after.”
• One of the most notable theories about time is Albert Einstein’s “Theory of Relativity” which states that “laws of physics are the same for all non-accelerating observers.” He said the speed of light within a vacuum is the same, no matter the speed at which an observer travels.
• The Egyptians are often credited for being the first civilization on earth to divide the day into smaller units of time due to their use of sundials.
• The most widely-used calendar is the Gregorian calendar.
• The first pendulum mechanical clock was made by Christiaan Huygens, a Dutch physicist, in 1656.