Convert between military time (24-hour) and standard time (AM/PM) instantly. Includes spoken form and full reference chart.
Military time, also called the 24-hour clock, runs from 0000 (midnight) to 2359 (one minute before the next midnight), eliminating the need for AM and PM designations. Each time of day has a unique 4-digit representation, removing the ambiguity that arises with the 12-hour clock where 3:00 appears twice daily. While primarily associated with the military, the 24-hour clock is standard in aviation, healthcare, computing, international business and most countries outside the United States and Canada.
Converting military time to standard time follows three simple rules. For times from 0000 to 1159 (midnight to 11:59 AM): these are AM times. Remove the leading zero if present and add AM. 0000 is 12:00 AM (midnight), 0100 is 1:00 AM, 0830 is 8:30 AM, 1145 is 11:45 AM. For 1200 (noon): this is 12:00 PM. The exception to all formulas — just remember that 1200 equals noon. For times from 1300 to 2359 (1:00 PM to 11:59 PM): these are PM times. Subtract 1200 from the military time and add PM. 1300 - 1200 = 100 = 1:00 PM. 1800 - 1200 = 600 = 6:00 PM. 2345 - 1200 = 1145 = 11:45 PM. Our time calculator handles adding and subtracting time durations and our date difference calculator computes the time between two dates and times.
| Military Time | Standard Time | Spoken | Period |
|---|---|---|---|
| 0000 | 12:00 AM | Zero hundred hours | Midnight |
| 0100 | 1:00 AM | Zero one hundred hours | Night |
| 0600 | 6:00 AM | Zero six hundred hours | Early morning |
| 0800 | 8:00 AM | Zero eight hundred hours | Morning |
| 1200 | 12:00 PM | Twelve hundred hours | Noon |
| 1300 | 1:00 PM | Thirteen hundred hours | Afternoon |
| 1630 | 4:30 PM | Sixteen thirty hours | Late afternoon |
| 1800 | 6:00 PM | Eighteen hundred hours | Evening |
| 2000 | 8:00 PM | Twenty hundred hours | Evening |
| 2359 | 11:59 PM | Twenty-three fifty-nine hours | Night |
Converting standard time (12-hour AM/PM) to military time is equally straightforward. For midnight (12:00 AM): write 0000. For AM times (1:00 AM to 11:59 AM): add a leading zero to make it 4 digits. 1:00 AM = 0100, 6:30 AM = 0630, 11:45 AM = 1145. For noon (12:00 PM): write 1200. For PM times (1:00 PM to 11:59 PM): add 1200 to the time. 1:00 PM = 0100 + 1200 = 1300. 4:30 PM = 0430 + 1200 = 1630. 11:59 PM = 1159 + 1200 = 2359. Military time is always written as exactly 4 digits with no colon. The format is HHMM where HH is the hour (00-23) and MM is the minute (00-59). Use our unit converter for other measurement conversions and our percentage calculator for related calculations.
The 24-hour clock is far more widespread globally than most Americans realise. It is the official time standard for aviation worldwide — every flight schedule, Air Traffic Control communication and NOTAM (Notice to Airmen) uses 24-hour time to prevent dangerous misunderstandings across time zones and languages. Hospitals and medical facilities in many countries use 24-hour time on medication schedules and patient records to prevent dosing errors — giving a medication "at 6" is ambiguous in a 12-hour context. The International Organization for Standardization (ISO 8601) standard, used in computing and international business documents, specifies 24-hour time notation. Most countries in Europe, Latin America, Asia and Africa use the 24-hour clock as their primary civil timekeeping system. In the United States, the military, emergency services (police, fire, EMS), railways, and many industries use 24-hour time operationally even though the general public uses 12-hour time. Programming and operating systems almost universally use 24-hour time internally — Unix timestamps, database datetime fields and log files default to 24-hour notation.
| Context | Time System | Example | Reason |
|---|---|---|---|
| US Military / NATO | 24-hour | 1430 hours | Eliminates AM/PM ambiguity |
| Commercial Aviation | 24-hour (Zulu) | 14:30Z | Global standard across time zones |
| Hospital medication charts | 24-hour | 14:30 | Prevents dosing errors |
| Most of Europe | 24-hour | 14:30 | Cultural standard |
| Computing / ISO 8601 | 24-hour | 14:30:00 | International standard |
| General US public | 12-hour | 2:30 PM | Historical convention |
Military operations and aviation use "Zulu time" (abbreviated Z), which is Coordinated Universal Time (UTC) — the global time standard. When the military says "operations begin at 0800Z", everyone worldwide knows exactly when that is regardless of their local time zone, because Zulu time has no offset. Each time zone is designated by a letter in military phonetics: Z is UTC (Zulu), A is UTC+1 (Alpha), B is UTC+2 (Bravo), and so on. Time zones west of UTC use letters from the later part of the alphabet: N is UTC-1 (November), Y is UTC-12 (Yankee). Local time in the continental US: R (Romeo) = Eastern Standard Time (UTC-5), S (Sierra) = Central (UTC-6), T (Tango) = Mountain (UTC-7), U (Uniform) = Pacific (UTC-8). During daylight saving time, these shift one hour. Understanding this system is essential for international military coordination and is why "1800Z" is used rather than "6 PM Eastern" in global operations.
Military time is pronounced as a 4-digit number followed by "hours", with specific conventions. Hours ending in 00 are pronounced as "X hundred hours": 0800 is "zero eight hundred hours", 1400 is "fourteen hundred hours", 2000 is "twenty hundred hours". Hours with non-zero minutes are pronounced with both parts: 0830 is "zero eight thirty hours", 1645 is "sixteen forty-five hours". Leading zeros are always spoken: 0045 is "zero zero forty-five hours". In informal military speech, "hours" is often dropped: soldiers may say "we meet at fourteen hundred" rather than "fourteen hundred hours." The word "oh" is sometimes used instead of "zero" in US military usage: 0800 can be "oh eight hundred". NATO phonetic alphabet is used for letters when spelling time zone designators: "0800 Zulu" is spoken as "zero eight hundred Zulu". Use our time calculator to add and subtract time intervals and our date difference calculator to calculate the duration between two military date-time groups.
The history of timekeeping standardisation is closely tied to military necessity. Before the widespread adoption of standard time zones in the late 19th century, each city set its own local time based on solar noon, creating chaos for railway scheduling and military coordination. The US adopted standard time zones in 1883, primarily driven by railroad companies needing coordinated scheduling. The military extension of this to a global 24-hour system was formalised through international agreements in the early 20th century as communication and coordination across great distances became operationally critical. NATO standardised the use of the 24-hour clock and the Zulu time zone for all alliance communications, ensuring that orders, intelligence reports and operational schedules could be interpreted without ambiguity by forces from different countries and time zones. Modern military communications still use this system, and civilian aviation adopted it globally for the same fundamental reason: when ambiguity costs lives, clarity is non-negotiable. Our time calculator is useful for adding and subtracting hours across time zone boundaries. International travel and business communication frequently requires understanding both the 24-hour clock and time zones simultaneously. When scheduling calls across time zones, the 24-hour system prevents the AM/PM error that causes missed meetings. "Let's speak at 9" is ambiguous without AM/PM and time zone; "let's speak at 0900 Eastern" is unambiguous. Business communication tools including email clients, calendar applications and project management platforms commonly store and display times in 24-hour format internally, converting to local 12-hour format for display. Understanding the underlying 24-hour format helps when reading server logs, database timestamps, API responses and other technical outputs that almost universally use ISO 8601 format (YYYY-MM-DDTHH:MM:SS). Healthcare workers who transition between hospital systems may encounter both 12-hour and 24-hour formats on medication charts and shift schedules. The US military uses a specific time format that appends the time zone letter: "1430R" means 2:30 PM Eastern Standard Time (Romeo). Flight itineraries always show local departure and arrival times in 24-hour format, which is why 14:30 appears on your boarding pass rather than 2:30 PM. Our time calculator handles time arithmetic across hours and minutes and our date difference calculator computes duration between any two date-time values.