How to Use a 24-Hour Clock

A 24-hour clock numbers the hours consecutively, starting from 00:00, or midnight, to 23:59 (11:59 p.

The 24-hour clock is used in the U.S. military.The 24-hour clock is used in the U.S. military.
m. , according to a 12-hour clock). The 24-hour system has long been used in the U. S. military, in computer systems and in Europe, where it is often referred to as "railroad time.

Turn on the 24-hour clock. Enter the "time set" mode.

Adjust the time to match an accurate 12-hour or 24-hour clock. From 1:00 a.m. until 12:00 p.m., the times are set identically on both 12- and 24-hour clocks. The equivalent of 1 p.m. for a 24-hour clock would be 13:00, for 2 p.m., 14:00 and so on consecutively until 23:59 (11:59 p.m.). Midnight on a 24-hour clock would be 00:00, rather than 12:00 a.m.

Reference the clock by reading the hours on the left of the colon and the minutes on the right, just as you would with a 12-hour clock. For example, 08:15 on a 24-hour clock is 8:15 a.m. on a 12-hour clock.

"Translate" the time into the a.m./p.m. system if you wish. When the hour shows any number above 12, subtract 12 from it. Thus, a reading of 16:30 on a 24-hour clock would be 4:30 p.m. on a 12-hour clock.


  • Set the hour change for daylight savings time just as you would on a 12-hour clock.
  • The time from a 24-hour clock is often reported in hundreds of hours. For example, 18:00 is generally referred to as "eighteen hundred hours." Nine o'clock in the morning on a 24-hour clock is commonly described as "o-nine hundred hours."
  • Some 24-hour clocks can be set automatically. Read the instructions for the specific clock model you are using to properly position and connect the clock with an available satellite.

About the Author

Jeffrey Brian Airman is a writer, musician and food blogger. A 15-year veteran of the restaurant industry, Airman has used his experience to cover food, restaurants, cooking and do-it-yourself projects. Airman also studied nursing at San Diego State University.