12 AM vs 12 PM
12 AM is midnight. 12 PM is noon. This is the most common point of confusion in the 12-hour clock.
Direct answer
12:00 AM equals 00:00. 12:00 PM equals 12:00. AM starts at midnight. PM starts at noon.
The short rule
12 AM
12 AM is midnight, the start of a new day. In 24-hour time, it is written as 00:00.
12 PM
12 PM is noon, the middle of the day. In 24-hour time, it is written as 12:00.
Why this confuses people
The 12-hour clock changes labels at exactly 12:00. The hour number does not reset to 1 until one hour later. That is why 12:30 AM is still after midnight, while 12:30 PM is after noon.
If the exact meaning matters, use words such as midnight or noon instead of only writing 12 AM or 12 PM. For travel, medicine, event deadlines, and technical logs, the 24-hour clock is often clearer.