Do you ever find yourself wondering how many hours there are between two times? Maybe you need to calculate your hours worked, or you’re planning a trip and need to know how long it will take to get there. Whatever the reason, understanding how to calculate hours can be a useful skill.

If you’re short on time, here’s a quick answer to your question: 8am to 3pm is 7 hours. But, if you want to learn more about how to calculate hours and other time-related topics, keep reading!

In this article, we will cover the basics of calculating hours and explore some common time-related questions. Here’s an overview of what we will include:

Understanding Time

Time is an important aspect of our lives, and understanding it is crucial. One of the most common questions people ask is how to calculate the number of hours between two times. To do this, it is important to understand the 24-hour clock.

The 24-hour clock

The 24-hour clock is a timekeeping system that uses 24 hours to represent a full day. It is also known as military time, and it is commonly used in many countries around the world. In the 24-hour clock system, the day begins at midnight, which is represented as 00:00, and ends at 23:59, which is the last minute of the day.

Using the 24-hour clock makes it easier to calculate the number of hours between two times. For example, if you want to calculate the number of hours between 8am and 3pm, you need to convert these times to the 24-hour clock. 8am is equivalent to 08:00, while 3pm is equivalent to 15:00.

AM and PM

AM and PM are abbreviations for ante meridiem and post meridiem, which mean before noon and after noon, respectively. These abbreviations are used in the 12-hour clock system, which is commonly used in the United States and other countries.

If you are using the 12-hour clock system, you need to add the appropriate AM or PM to the time. For example, 8am is equivalent to 08:00 AM, while 3pm is equivalent to 03:00 PM.

However, it is important to note that the 12-hour clock system can be confusing, especially when calculating the number of hours between two times. This is why it is recommended to use the 24-hour clock system, which is more straightforward and easier to understand.

Calculating Hours

Whether you’re trying to figure out how many hours you worked in a week or how long it took you to finish a project, calculating hours is an essential skill. Here are two methods you can use:

Subtraction Method

The subtraction method is a straightforward way to calculate the number of hours between two times. Simply subtract the start time from the end time.

For example, if you started work at 8am and finished at 3pm, you would subtract 8am from 3pm:

End Time Start Time Hours Worked
3pm 8am 7 hours

Using the subtraction method, you can calculate the number of hours worked or the duration of any event.

Addition Method

The addition method is useful when you have a start time and a duration but need to know the end time.

For example, if you started a project at 8am and it took you 5 hours to complete, you would add 5 hours to 8am:

Start Time Duration End Time
8am 5 hours 1pm

Using the addition method, you can calculate when an event will end or how long it will take to complete.

Remember, calculating hours is an important skill that can help you manage your time effectively and make sure you get paid for the hours you work. If you need more help, there are plenty of resources available online, such as Calculator Soup’s hours calculator.

Time Calculations in Everyday Life

Time calculations are a part of our daily routine, and we often need to calculate time for various purposes, such as work, travel, or personal schedules. Here are some examples of how time calculations can be used in everyday life:

Calculating Work Hours

Calculating work hours is essential for employees and employers alike. It helps to ensure that employees are paid accurately for the time they work, and employers can track their labor costs. For example, if an employee starts work at 8 am and finishes at 3 pm, the total hours worked would be 7 hours.

By calculating work hours, employees can also keep track of their overtime hours, which can be useful for negotiating pay or time off. Some companies use time tracking software to automatically calculate the hours worked, but it’s always a good idea to double-check the calculations.

Planning Travel Time

Another instance where time calculations are important is when planning travel time. Whether it’s for a daily commute or a road trip, knowing how long it will take to get from point A to point B can help you plan your day better. For example, if you need to be at work by 9 am and it takes 45 minutes to get there, you’ll need to leave home by 8:15 am.

There are many tools available online to help you calculate travel time, such as Google Maps or Waze. These tools take into account traffic patterns, road closures, and other factors that can affect your travel time.

Time Management Tips

Time management is an essential skill that can help you be more productive and achieve your goals. One way to improve time management is by setting specific goals and deadlines. For example, if you have a project due in two weeks, break it down into smaller tasks and set deadlines for each task.

Another time management tip is to prioritize your tasks. Make a to-do list and rank your tasks in order of importance. This will help you focus on the most critical tasks first and avoid wasting time on less important tasks.

Finally, it’s essential to take breaks and manage your energy levels. Working too long without taking breaks can lead to burnout and decreased productivity. Schedule regular breaks throughout the day to recharge your batteries and stay focused.


Time calculations are an essential part of our daily lives, and we use them for various purposes, such as work, travel, and personal schedules. By understanding how to calculate time accurately and manage it effectively, we can be more productive, achieve our goals, and enjoy a better quality of life.

Time-Related Terminology

When it comes to measuring time, there are different units that we use to determine the duration of an event. The most basic units of time are seconds, minutes, and hours. A second is the smallest unit of time that we use, and it is equal to 1/60th of a minute or 1/3600th of an hour. A minute is equal to 60 seconds, while an hour is equal to 60 minutes or 3,600 seconds.

Days, weeks, and months are larger units of time that we use to measure longer periods. A day is equal to 24 hours, while a week is equal to 7 days. A month can have 28, 30, or 31 days, depending on the month.

Leap years and daylight saving time are two time-related concepts that can affect how we measure time. A leap year is a year that has an extra day added to it, which is February 29th. This is done to keep the calendar year synchronized with the solar year. Daylight saving time, on the other hand, is the practice of moving the clock forward by one hour during the summer months to extend the amount of daylight in the evening.

Unit of Time Equivalent
1 second 1/60th of a minute or 1/3600th of an hour
1 minute 60 seconds
1 hour 60 minutes or 3,600 seconds
1 day 24 hours
1 week 7 days

For more information on time-related terminology, you can visit the National Institute of Standards and Technology website.


Knowing how to calculate hours and understand time-related concepts is an essential skill that can help you in many areas of life. Whether you’re calculating your work hours, planning a trip, or just trying to manage your time better, understanding time can make your life easier.

We hope this article has given you a better understanding of time and how to calculate hours. If you have any questions or comments, feel free to leave them below!

Remember, time is a precious resource, so use it wisely!

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