24 Hour to 12 Hour Time Converter

What is 24 hour time?

The 24 hour clock numbers the hours of a day from 0 to 23 and does not need AM or PM. A day starts at 00:00 (midnight), noon is 12:00, and the last minute of the day is 23:59. Because every hour has a unique number, a time such as 17:30 cannot be misread as morning.

It is the usual way of writing times in much of Europe and Asia, and the default in aviation, rail timetables, hospitals, computing and the armed forces. The 12 hour clock, with its AM and PM halves, remains common in the United States, Canada, Australia and the Philippines. Switching between the two is a matter of simple arithmetic.

How to convert between 24 hour and 12 hour time

From 24 hour to 12 hour:

• Hour 0 becomes 12 AM (midnight). Minutes are unchanged.
• Hours 1 to 11 stay the same and take AM.
• Hour 12 stays 12 and takes PM (noon).
• Hours 13 to 23 lose 12 and take PM.

12 hour value = hour − 12 (for hours 13 to 23, PM)

From 12 hour to 24 hour:

• 12 AM becomes hour 0.
• 1 AM to 11 AM stay the same.
• 12 PM stays 12.
• 1 PM to 11 PM gain 12.

24 hour value = hour + 12 (for 1 PM to 11 PM)

In the converter, use the Convert option to pick the direction. Type 24 hour times with or without the colon (17:30 or 1730; three digits such as 930 also work) and 12 hour times with AM or PM (5:30 PM, 05:30 pm or 530pm). Hours run from 0 to 24 and minutes from 00 to 59, so a time like 14:75 leaves the answer box empty. For times just after midnight or around noon, glance at the chart below, since 12 is the hour people mix up most.

Worked examples

24 hour to 12 hour. 17:30 is an afternoon hour above 12, so subtract 12: 17 − 12 = 5, giving 5:30 PM. 00:15 is hour 0, which becomes 12: 12:15 AM. 12:45 is already 12, so it is 12:45 PM. 09:05 is below 12 and becomes 9:05 AM.

12 hour to 24 hour. 5:30 PM is a PM hour from 1 to 11, so add 12: 5 + 12 = 17, giving 17:30. 12:05 AM is just after midnight, so it is 00:05. 12:40 PM stays 12:40. 7:20 AM stays 07:20.

Quick check. Whatever the direction, the minutes never change. Only the hour is rewritten, and only when it is 0, 12 or above.

24 hour clock conversion chart

Midnight, noon and 24:00

12:00 AM is midnight and 12:00 PM is noon. AM stands for ante meridiem (before midday) and PM for post meridiem (after midday), so noon itself is neither strictly before nor after. Writing "12 noon" or "12 midnight" avoids any doubt.

Midnight has two 24 hour spellings. 00:00 marks the start of a day, while 24:00 is sometimes used in schedules to mean the end of that same day. A timetable that says a shop closes at 24:00 on Monday means the moment Tuesday begins.

Related time tools

• The military time converter reads and writes four-digit times such as 2030.
• To measure the gap between two clock times, use the hours between times calculator.
• For durations in seconds, minutes, hours and days, use the time converter.