The 24-hour military time system

Most people learn how to read a watch to see what time it is at a young age. They use the same system throughout their lifetimes and wouldn’t think of it as something that could be confusing.

That might change for you if you have just enrolled in boot camp or you are thinking about a career in the military. It is important to understand the 24-hour military time system before interacting with military personnel.

In the military world, time is referred to using this system. Without understanding how it works, you could be late to an important drill or meeting. In this guide, we’ll cover what the 24-hour military time system is, why it exists, how it operates against time zones, and we’ll provide you with a detailed chart that breaks down military time into civilian time.

What is the 24-hour military time system?

For most civilians, the time of day is referenced based on 12-hour periods. These 12-hour periods are followed by a.m. or p.m. to indicate whether it is daytime or nighttime. For example, if you were to set a meeting with your boss for nine in the morning, you would request a meeting for 9:00 a.m. Conversely, if you planned to meet later in the day, you would ask to get together at 3:00 p.m.

The military uses a 24-hour time system instead. Rather than denoting the time of day with a.m. or p.m. the period in time is indicated by using a full 24-hour clock.

When referencing military time, the 24 hours on a clock are translated into segments of hundreds. Anything prior to double digits is preceded by a zero, which is spoken as an “O.” For example, 4:00 a.m. in military time is 0400, which you would state as “O Four Hundred.” For double digits, the number is simply followed by the word “hundred,” e.g., “Thirteen Hundred.”

Quick Tip: Need to quickly translate civilian time into military time? If the hour is before noon, refer to the time as the number followed by hundred. For example, if you want to set up a 9:00 a.m. meeting, you would simply refer to the time as “O Nine Hundred.” If the time is later than noon, just add the hour to the number 12. For example, a 3:00 p.m. meeting would be 12+3, or 1500 time. See a complete list of time translations below.

24-hour military time system chart

If you need to quickly translate civilian time into military time, use the following handy chart:

Why does the military use the 24-hour system?

One of the benefits of the 24-hour military time system is that it helps reduce confusion. Because everything operates on a 24-hour time scale, there is less chance of error than with a.m. and p.m. time stamps. This becomes even more important when military personnel discuss times and dates across time zones.

Additionally, the abbreviated format of the 24-hour system makes it easier to send concise communications. When it comes to military drills and critical missions, the efficiency and accuracy of the 24-hour system can actually mean life or death.

Using military time across time zones

To avoid confusion when discussing times and dates across time zones, the military uses the Greenwich Mean Time (GMT). Greenwich Mean Time (GMT) is a 24-hour time-keeping system, which uses the earth’s prime meridian located near Greenwich, England, as its center. This allows military personnel to converse about a specific time based on the same time zone foundation.

From here, personnel must translate this time into their own time zone.

For example, communication about the location of a platoon might read, “Platoon 4 will be located at [coordinates] at 2300 GMT.” Local military personnel would then translate this into their current time zone.

Generally, when conversing with other military personnel in the same time zone, you will use the local time zone rather than GMT.

Practicing the 24-hour military time system

The 24-hour military time system can feel overwhelming when you are not accustomed to using it on a day-to-day basis. However, with a little practice, this time system will quickly become an effective means for communicating time without the risk of confusing a.m. and p.m.

To practice using the 24-hour military time system, try a few of the following exercises:

1. Draw a clock that uses a 24-hour scale instead of the normal 12-hour scale. By visualizing the 24-hour clock, you’ll make it easier to tell time.
2. Practice using military time around the home. With your spouse, roommate, or children, start making plans using the 24-hour time system.
3. Have a friend or family member quiz you. It is often easier to tell time in the military format than to hear and comprehend a time that is given to you. Have your chosen assistant state a military time. Then, repeat back the time in the civilian format. Make sure that the person assisting you has a chart handy so they can correct you as you go.
4. Write out your daily schedule using the 24-hour system. By writing your daily schedule in a 24-hour format, you can become accustomed to thinking of your day-to-day life in this way.

Remember, practice makes perfect when you are learning how to use the 24-hour military time system. While it might seem difficult at first, you could ultimately decide that you prefer this logic-based system.