AM/PM to 24-Hour Converter
Convert between 12-hour and 24-hour time formats instantly.
Last updated: April 2026
Common times:
12-hour time:
24-hour time:
| Format | Result |
|---|---|
| 12-hour | 12:00 AM |
| 24-hour | 00:00 |
Common conversions
| 24-hour | 12-hour AM/PM |
|---|---|
| 13:00 | 1:00 PM |
| 14:00 | 2:00 PM |
| 15:00 | 3:00 PM |
| 16:00 | 4:00 PM |
| 17:00 | 5:00 PM |
| 18:00 | 6:00 PM |
| 19:00 | 7:00 PM |
| 20:00 | 8:00 PM |
The 12-hour and 24-hour clock systems both measure the same thing — the position of the day — but they express it differently. The 12-hour format splits the day into two AM and PM halves, each running from 12 to 11. The 24-hour format counts straight through from 00:00 to 23:59. Both are in daily use worldwide, but the choice of format often depends on country, profession, or context.
When do you need this?
- Booking international flights — departure and arrival times are shown in local 24-hour format at many airports.
- Reading train and bus timetables in Europe, Asia, and most of the world outside North America.
- Scheduling video calls across time zones — a 15:00 UTC meeting is instantly clear; "3 PM UTC" requires a moment of mental translation.
- Medical and shift work — hospital rosters, medication schedules, and lab timestamps always use 24-hour time to prevent errors.
- Military and aviation communication, where "fifteen hundred hours" eliminates any risk of AM/PM confusion.
- Reading digital device timestamps, log files, or spreadsheet exports from systems configured to 24-hour output.
Quick reference
- AM to 24-hour: keep the hour as-is (1 AM → 01:00), except 12 AM → 00:00.
- PM to 24-hour: add 12 to the hour (3 PM → 15:00), except 12 PM stays 12:00.
- 24-hour to AM/PM: subtract 12 if the hour is 13 or higher (17:00 → 5 PM). 00:xx → 12:xx AM.
- Midnight: 12:00 AM = 00:00. Noon: 12:00 PM = 12:00.
- End of day: 11:59 PM = 23:59. There is no 24:00 — the next second is 00:00.
Understanding the formats
12-hour (AM/PM)
The 12-hour clock divides the day into two identical 12-hour periods: AM (ante meridiem — before midday) and PM (post meridiem — after midday). Each runs from 12 to 11, which is counterintuitive: the first hour of the AM period is 12, not 1. This quirk is the source of most confusion around midnight and noon.
It is the default in everyday speech and consumer devices in the United States, Canada, Australia, and the United Kingdom. Clocks, smartphones, and 12-hour-format countries show times like "3:45 PM" or "11:00 AM".
24-hour (military time)
The 24-hour clock counts from 00:00 (midnight) to 23:59 (one minute before the next midnight). There is no AM or PM — the hour alone tells you whether it is morning or evening. 08:00 is always morning; 20:00 is always evening.
It is the international standard for aviation, railways, the military, medicine, and most scientific and technical contexts. In everyday use it is standard across Europe, Latin America, most of Asia, and Africa. Spoken aloud, 15:30 is typically said as "fifteen thirty".
Common mistakes
- Confusing 12:00 AM and 12:00 PM. 12:00 AM is midnight; 12:00 PM is noon. Many people assume the opposite. When in doubt, use 00:00 and 12:00.
- Adding 12 to 12 PM. 12 PM is already noon (12:00) — do not turn it into 24:00, which does not exist.
- Forgetting the leading zero for AM hours below 10. 9 AM is 09:00 in 24-hour notation. Official formats require the leading zero.
- Assuming midnight belongs to the current day. 00:00 Tuesday is the very start of Tuesday — not the end of Monday. This matters for flight bookings and calendar events.
- Treating time zone offsets and format as the same problem. Converting AM/PM to 24-hour is a format change only — it does not change what moment in time you are describing.
Which should you use?
Writing a formal schedule, ticket, or official document: use 24-hour. It is unambiguous and internationally understood.
Talking to someone in the US or UK in casual context: AM/PM is what they expect and will read fastest.
Coordinating across time zones: always specify the UTC offset alongside the time, regardless of format — "15:00 UTC+1" or "3:00 PM UTC+1" both work.
Medical or safety-critical contexts: 24-hour format only. Ambiguity between AM and PM has caused real errors in medication administration and incident reporting.
World city UTC offsets
| City | UTC offset (standard / summer) |
|---|---|
| London | UTC+0 / UTC+1 (BST) |
| Paris / Berlin | UTC+1 / UTC+2 (CEST) |
| Dubai | UTC+4 (no DST) |
| Mumbai | UTC+5:30 (no DST) |
| Singapore | UTC+8 (no DST) |
| Tokyo | UTC+9 (no DST) |
| Sydney | UTC+10 / UTC+11 (AEDT) |
| New York | UTC−5 / UTC−4 (EDT) |
| Los Angeles | UTC−8 / UTC−7 (PDT) |
Frequently asked questions
What is 12:00 AM in 24-hour time?
12:00 AM is midnight, written as 00:00 in 24-hour format. It marks the very start of a new day.
What is 12:00 PM in 24-hour time?
12:00 PM is noon, written as 12:00 in 24-hour format. It is the only PM hour that does not require adding 12.
How do I convert PM to 24-hour time?
For PM times, add 12 to the hour — except for 12 PM which stays as 12:00. For example, 3:00 PM becomes 15:00, and 11:30 PM becomes 23:30.
What time is 00:00?
00:00 in 24-hour time is midnight — the very start of a new day. It is written as 12:00 AM in 12-hour format. The last minute of the day is 23:59, which corresponds to 11:59 PM.
Why do some countries use AM/PM and others use 24-hour time?
The 12-hour AM/PM system has roots in ancient Egypt and Rome, and was carried into widespread use through British influence. The 24-hour clock became standard in military, aviation, and medical contexts worldwide because it eliminates ambiguity. Most of Europe and Asia uses 24-hour time in official contexts, while the US, UK, Australia and a few others still commonly use the 12-hour format in everyday life.
Is 12:00 AM noon or midnight?
12:00 AM is midnight, not noon. 12:00 PM is noon. This is one of the most commonly confused points in the 12-hour system. The 24-hour equivalents — 00:00 for midnight and 12:00 for noon — are completely unambiguous.
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