# Military time converter (24-hour time)

> Military time converter: 12-hour to 24-hour time and back, how it is spoken, time-zone letters with the Zulu equivalent, and a full-day chart.

交互版本：https://www.calcopenly.com/zh/datetime/military-time-converter
主题：日期与时间计算器

Military time writes the hour from 00 to 23 followed by the minutes, as four digits with no colon: 7:45 PM is 1945 and 12:30 AM is 0030. To convert an afternoon time, add 12 to the hour; to go back, subtract 12 from any hour from 13 to 23 and write PM. Noon is 1200 and midnight at the start of the day is 0000.

Type a time either way, with AM or PM, with a colon or as four digits. The converter gives the military, 24-hour and 12-hour forms, how the time is said aloud ("nineteen forty-five hours"), the digit-by-digit radio form, and a chart of all 24 hours. A zone letter after the digits, such as 1945R for US Eastern Standard Time, is turned into the matching Zulu (UTC) time.

The letters are fixed whole-hour offsets from UTC and ignore daylight saving time, so the zone that matches a place changes when its clocks change.

## 输入

- **时间**: 12-hour (7:45 pm, 7pm), 24-hour (19:45) or military (1945). A zone letter can follow, as in 1945Z.
- **Time-zone letter**: Adds the military zone suffix and converts to Zulu (UTC). A letter typed after the time overrides this. (选项：No zone letter, Z (Zulu) UTC, A (Alfa) UTC+1, B (Bravo) UTC+2, C (Charlie) UTC+3, D (Delta) UTC+4, E (Echo) UTC+5, F (Foxtrot) UTC+6, G (Golf) UTC+7, H (Hotel) UTC+8, I (India) UTC+9, K (Kilo) UTC+10, L (Lima) UTC+11, M (Mike) UTC+12, N (November) UTC−1, O (Oscar) UTC−2, P (Papa) UTC−3, Q (Quebec) UTC−4, R (Romeo) UTC−5, S (Sierra) UTC−6, T (Tango) UTC−7, U (Uniform) UTC−8, V (Victor) UTC−9, W (Whiskey) UTC−10, X (X-ray) UTC−11, Y (Yankee) UTC−12, J (Juliett) local time)
- **Write a date-time group**
- **Date**: The date in the time zone of the time above.

## 结果

- 24 小时制时间 — 主要结果
- 24-hour clock
- 12-hour clock
- Spoken
- Spoken digit by digit (radio)
- With zone letter
- Zulu (UTC) time
- Date-time group
- Date-time group in Zulu
- Hours since midnight (h)

## 公式

$$
\text{military} = \begin{cases} h & \text{AM},\ h \ne 12 \\ 0 & 12\ \text{AM} \\ 12 & 12\ \text{PM} \\ h + 12 & \text{PM},\ h \ne 12 \end{cases}
$$

## 计算示例

### 7:45 PM

- 时间: 7:45 PM
- Time-zone letter: No zone letter
- **24 小时制时间: 1945**
- **24-hour clock: 19:45**
- **Spoken: nineteen forty-five hours**
- **Spoken digit by digit (radio): one niner four five**
- **With zone letter: 不适用**
- 核验来源：Add 12 to a PM hour; spoken in hundreds per Navy BMR ch. 3; digit words and “niner” from ACP 125(G) Table 3-2

### Army example: 1:37 p.m.

- 时间: 1:37 p.m.
- Time-zone letter: No zone letter
- **24 小时制时间: 1337**
- 核验来源：AR 25-50 para 1-26: “1:37 p.m. civilian time is expressed as 1337 military time”

### Navy example: 0100

- 时间: 0100
- Time-zone letter: No zone letter
- **12-hour clock: 1:00 AM**
- **Spoken: zero one hundred hours**
- 核验来源：Navy BMR (NAVEDTRA 14325) ch. 3: “0100 (1:00 a.m.) is spoken ‘zero one hundred’”

### Navy example: 2315

- 时间: 2315
- Time-zone letter: No zone letter
- **12-hour clock: 11:15 PM**
- **Spoken: twenty-three fifteen hours**
- 核验来源：Navy BMR ch. 3: “2315 (11:15 p.m.) is spoken ‘twenty three fifteen’”

### Navy example: 2000

- 时间: 2000
- Time-zone letter: No zone letter
- **12-hour clock: 8:00 PM**
- **Spoken: twenty hundred hours**
- 核验来源：Navy BMR ch. 3: “2000 (8 p.m.) is pronounced ‘twenty hundred’”

### Radio: 1630

- 时间: 1630
- Time-zone letter: No zone letter
- **Spoken: sixteen thirty hours**
- **Spoken digit by digit (radio): one six three zero**
- 核验来源：ACP 125(G) Table 3-3: “Sixteen thirty hours”, or “one six three zero hours” digit by digit

## 常见问题

### How do you convert standard time to military time?

Keep AM hours as they are with a leading zero, write 12 AM as 00, keep 12 PM as 12, and add 12 to any other PM hour. Then write the hour and minutes as four digits without a colon: 7:45 PM is 1945 and 6:05 AM is 0605. Army Regulation 25-50 gives 1:37 p.m. as 1337 and says the word "hours" is not written after military time.

### How do you say military time out loud?

In hundreds, pair by pair. The US Navy's Basic Military Requirements manual gives 0100 as "zero one hundred", 2000 as "twenty hundred" and 2315 as "twenty three fifteen"; "hours" is usually added in speech, as in ACP 125's "sixteen thirty hours". Official sources say "zero", not "oh". On a radio net, date-time groups and times in poor conditions are read digit by digit: one six three zero, with nine said "niner".

### Is midnight 0000 or 2400 in military time?

Both appear. The Navy's Basic Military Requirements manual uses 0000 for the start of a day and 2400 for its end. The Navy correspondence manual (SECNAV M-5216.5) runs times from 0000 to 2359, while Army Regulation 25-50 runs from 0001 to 2400. ACP 121, the Allied communications standard, advises writing 2359 or 0001 in messages to avoid the ambiguity.

### What does Zulu time mean?

Zulu is the military name for UTC, the zone letter Z. Letters A to M (J skipped) are UTC+1 to UTC+12, N to Y are UTC−1 to UTC−12, and J (Juliett) means the observer's local time (Army ATP 6-02.70, Table E-1). Washington, DC in winter is zone R, UTC−5, so 1945R is 0045Z the next day. The letters are whole-hour offsets; ATP 6-02.70 marks a half-hour zone with an asterisk, as in 0430D* for Afghanistan (UTC+4:30).

### What is a date-time group?

It is how military messages stamp a date and time: two digits for the day, four for the time, the zone letter, then the month's first three letters and the year's last two digits. ACP 121(G) gives 271630Z JUN 03 as 16:30 UTC on 27 June 2003. Switch on "Write a date-time group" under More options to build one, in your zone and in Zulu.

### “Military time converter (24-hour time)”有多准确？

准确性取决于输入值和方法的假设。十进制运算使用50位有效数字，但估算、数值方法和源数据的精度可能较低；显示时的舍入并不能消除这些限制。 已按独立来源核验的计算示例：11。 例如，“7:45 PM”根据Add 12 to a PM hour; spoken in hundreds per Navy BMR ch. 3; digit words and “niner” from ACP 125(G) Table 3-2进行核验。

### 这种方法出自哪里？

US Army ATP 6-02.70, Techniques for Spectrum Management Operations (2015), Appendix E: time zones, Table E-1 (copy at bits.de); Combined Communications-Electronics Board, ACP 121(G) Communication instructions — general, para 317 and 325, Annex A to chapter 3 (copy at navy-radio.com); Combined Communications-Electronics Board, ACP 125(G) Radiotelephone procedures, Tables 3-2 and 3-3 (copy at Civil Air Patrol); US Navy NAVEDTRA 14325, Basic Military Requirements, chapter 3: military time (copy at navytribe.com); US Army Regulation 25-50, Preparing and Managing Correspondence (2020), para 1-26; US Coast Guard CGTTP 6-01.1B Radiotelephone Handbook (2018).

## 来源

- [US Army ATP 6-02.70, Techniques for Spectrum Management Operations (2015), Appendix E: time zones, Table E-1 (copy at bits.de)](https://www.bits.de/NRANEU/others/amd-us-archive/ATP6-02.70(15).pdf)
- [Combined Communications-Electronics Board, ACP 121(G) Communication instructions — general, para 317 and 325, Annex A to chapter 3 (copy at navy-radio.com)](https://www.navy-radio.com/manuals/acp/acp121g.pdf)
- [Combined Communications-Electronics Board, ACP 125(G) Radiotelephone procedures, Tables 3-2 and 3-3 (copy at Civil Air Patrol)](https://orwg.cap.gov/media/cms/ACP125GRadioTelephoneProceduresNOV2_EFFE1A51BA783.pdf)
- [US Navy NAVEDTRA 14325, Basic Military Requirements, chapter 3: military time (copy at navytribe.com)](https://navytribe.com/wp-content/uploads/2015/08/navedtra-14325.pdf)
- US Army Regulation 25-50, Preparing and Managing Correspondence (2020), para 1-26
- [US Coast Guard CGTTP 6-01.1B Radiotelephone Handbook (2018)](https://www.cisa.gov/sites/default/files/publications/CGTTP_6-01_1B_Radiotelephone_Handbook.pdf)