Military Time Mayhem Understanding the 24-Hour Clock

There are two types of “time” that we use

⦁12-hour clock (most commonly used by Americans)
⦁24-hour clock (Military Time)

See example of clock below:
red indicates 24-hour clock (military time)
⦁black indicates 12-hour clock (regular time) which most use

12-Hour Clock (what we use)

24 Hour Clock (Military Time)

10:10 A.M.

2214 hours

Military time is not limited to our armed forces, but also serves a multitude of professions, government entities, and industries. 

  • Airlines
  • Medical Entities (hospitals, coroners, physicians, etc.)
  • Military
  • Public Transit (train, bus, subway)
  • Government
  • Science 

Military time is the preferred term given to a 24-hour clock.

The reason this system is used is to avoid any confusion or errors when referencing time.

When using regular time, it’s easy to say “5:00 o’clock” but does that mean A.M. or P.M.?

table clock

Mistakes have been made in using regular time because of an example such as this.

With the 24-hour clock, there is no A.M. or P.M.

The 24-hour clock (military time):
⦁Begins at 0000 hours
⦁Ends at 2300 hours 

Standard Of Telling Time Around the World

Some countries (including the U.S.) refer to the 24-hour clock as “military time.”

Many foreign countries use the 24-hour clock standard and have done so for hundreds of years.

24 clock

The International Organization for Standardization (ISO) is a standard by which the world adopts and communicates times and dates.

Under the ISO, there is only one way to communicate time and date.

Time:0000-2300 hours (24-hour clock) (written as 00:00 - 23:00) Date: YYYY-MM-DD (written as 2018-12-01)

If you will notice, next time you are filling out forms, the ISO standard is reflected on the form.

Most of us fail to write the date correctly (Year/Month/Day) on forms because we are so accustomed to the regular way of time/date.

Converting Regular Time to 24-Hour Clock (Military Time)

A trick in trying to convert military time into regular time and vice versa includes doing a little bit of math in your head but works quickly.

geometry

1:00 A.M. to 9:30 A.M.
⦁Add a “0” (zero) in front of the time to get military time (example: 0100, 0930)

10:00 A.M. to 12:00 P.M.
⦁1000 hours
⦁1030 hours
⦁1100 hours
⦁1130 hours
⦁1200 hours

1:00 P.M. to 11:30 P.M.
⦁Simply add “12” to time 
⦁(example: 1:00 P.M. + 12 = 13:00)

12:00 A.M.
⦁Easily remembered as four zeros “0000”

Cheat Charts for Converting Time


Morning

12 Hour Clock

24 Hour Military Time

12 Hour Clock

24 Hour Military Time

12:00 Midnight

0000

6:00 AM

0600

12:15 AM

0015

6:15 AM

0615

12:30 AM

0030

6:30 AM

0630

12:45 AM

0045

6:45 AM

0645

1:00 AM

0100

7:00 AM

0700

1:15 AM

0115

7:15 AM

0715

1:30 AM

0130

7:30 AM

0730

1:45 AM

0145

7:45 AM

0745

2:00 AM

0200

8:00 AM

0800

2:15 AM

0215

8:15 AM

0815

2:30 AM

0230

8:30 AM

0830

2:45: AM

0245

8:45 AM

0845

3:00 AM

0300

9:00 AM

0900

3:15 AM

0315

9:15 AM

0915

3:30 AM

0330

9:30 AM

0930

3:45 AM

0345

9:45 AM

0945

4:00 AM

0400

10:00 AM

1000

4:15 AM

0415

10:15 AM

1015

4:30 AM

0430

10:30 AM

1030

4:45 AM

0445

10:45 AM

1045

5:00 AM

0500

11:00 AM

1100

5:15 AM

0515

11:15 AM

1115

5:30 AM

0530

11:30 AM

1130

5:40 AM

0540

11:45 AM

1145


Evening

12 Hour Clock

24 Hour Military Time

12 Hour Clock

24 Hour Military Time

12:00 Midnight

1200

6:00 PM

1800

12:15 PM

1215

6:15 PM

1815

12:30 PM

1230

6:30 PM

1830

12:45 PM

1245

6:45 PM

1845

1:00 PM

1300

7:00 PM

1900

1:15 PM

1315

7:15 PM

1915

1:30 PM

1330

7:30 PM

1930

1:45 PM

1345

7:45 PM

1945

2:00 PM

1400

8:00 PM

2000

2:15 PM

1415

8:15 PM

2015

2:30 PM

1430

8:30 PM

2030

2:45: PM

1445

8:45 PM

2045

3:00 PM

1500

9:00 PM

2100

3:15 PM

1515

9:15 PM

2115

3:30 PM

1530

9:30 PM

2130

3:45 PM

1545

9:45 PM

2145

4:00 PM

1600

10:00 PM

2200

4:15 PM

1615

10:15 PM

2215

4:30 PM

1630

10:30 PM

2230

4:45 PM

1645

10:45 PM

2245

5:00 PM

1700

11:00 PM

2300

5:15 PM

1715

11:15 PM

2315

5:30 PM

1730

11:30 PM

2330

5:40 PM

1745

11:45 PM

2345

Mastering Military Time…

By following the above shortcuts to converting regular time to military time and by using the charts we have provided, you can easily be spot on with the 24-hour clock!

Fun Facts About Time! 

  • The first clock was used by the Mesopotamians and Egyptians. Their clock was a sundial which calculated time. During the night they used a water clock.
  • A full day is actually not 24 hours but rather 23 hours, 56 minutes, 4.2 seconds.
  • By the time we see something, it is 8 minutes and 20 seconds old (from the past.) That’s how long it takes light to reach us.
  • One single day on the planet Mercury is equivalent to two years on earth.

References

Thorsen, S. (1995-2018) History of Daylight Saving Time (DST), Retrieved from:https://www.timeanddate.com/

Mosher, D. (2018 March 10) Daylight Saving Time begins on Sunday, and you should be furious, Retrieved from:
https://www.businessinsider.com/when-does-daylight-savings-time-start-march-2018-3