24-hour clock to and from AM / PM
Type a time either way, 1730 or 5:30 pm, and see the other at once, with how to say it out loud.
Military time numbers the hours of the day from 00 to 23 and writes a time as four digits, with no colon and no AM or PM. Find the hour below; the minutes never change.
Then leave out the colon and the AM or PM.
Say the hour as one number and the minutes as another. On the hour, say “hundred”. A leading zero is said too: the manuals say “zero”, though you may also hear “oh”.
A time followed by Z, like 1730Z, is Zulu time: Coordinated Universal Time (UTC). Each military time zone has a letter and a code word, from Alfa (UTC+1) to Yankee (UTC−12).
Both name midnight: 2400 at the end of Monday is the same moment as 0000 at the start of Tuesday. NIST, the U.S. National Institute of Standards and Technology, suggests 0000 for the start of a day and 2400 for its end. Military manuals differ: the Army's correspondence rules write 0001 to 2400, the Navy's correspondence manual has written 0000 to 2359 since 2015, and Allied message rules avoid 2400 where they can. More on midnight.
1200 is noon, 12:00 PM. Midnight is 0000 (or 2400).
Military time is the 24-hour clock written as four digits: the Navy's and the Air Force's writing rules leave the colon out, so it is 0930, not 09:30.
Often, when speaking: “seventeen thirty hours”. In writing, the Army and the Air Force say to leave “hours” out.
The manuals say “zero”: 0700 is “zero seven hundred”, and the Navy's training manual gives 0100 as “zero one hundred”. In everyday speech you may also hear “oh seven hundred”.
Z stands for Zulu, the military name for Coordinated Universal Time (UTC). 1730Z is 5:30 PM in UTC, which is 1:30 PM in New York in summer (EDT) and 12:30 PM in winter (EST).
Need the hours between two times, for a shift or a timecard? Use the military time calculator.