Clarifying the Use of 12 PM and 12 AM in Time Reckoning

The terms 12 PM and 12 AM are often met with confusion regarding their correct usage. This article aims to provide a clear understanding of what these terms represent and why they are used, dispelling common misunderstandings and settling the debate once and for all.

Understanding 12 PM and 12 AM

The terms '12 AM' and '12 PM' are used to indicate the hours within a 12-hour clock format. According to the standard interpretation:

12 AM: refers to midnight, marking the start of a new day. 12 PM: refers to noon, the middle of the day.

However, this understanding can be challenged due to the literal and practical misuse of these terms.

Technically Correct Definitions

Technically Incorrect: The term 12 PM is often cited as 'post meridiem,' implying 'after noon.' But since noon itself is the middle of the day, it cannot be after itself. The same logic applies to 12 AM, which is 'ante meridiem,' or 'before noon.'

Therefore, it can be argued that 12 AM and 12 PM are indeed technically incorrect when used in their strictest sense. To avoid confusion, it is often recommended to use the more explicit terms 'midnight' and 'noon.'

Widely Accepted Usage

Despite the technical inaccuracy, 12 PM and 12 AM are widely accepted due to practical convenience. The reason for this acceptance is rooted in practical usage and compatibility:

12:01 PM is officially one minute after noon. 12:00 PM, although technically incorrect, represents noon itself, serving as a convenient shorthand. 12:00 PM is used consistently across various time logs and computer systems, promoting uniformity.

Practical Considerations

From a practical standpoint, 12 PM is often seen as part of the post-meridian time, meaning the time that comes after noon. This is because:

By the time events at noon are noted, they are already technically past noon by a very small margin. Therefore, 12:00 is by convention considered part of the post-meridian time. Times such as 12:00:30 PM, 12:00:01 PM, and even 12:00:00.5 PM are all post-meridian.

However, some have proposed alternatives, such as using the term 'm' for meridian, with 12:00 m representing noon. This usage is less practical due to its ambiguity and the tendency to misinterpret 12:00 m to mean post-meridian time.

Conclusion

While technically incorrect, the terms 12 PM and 12 AM are widely accepted due to their practical utility. For precise and unambiguous communication, especially in academic or official settings, it is best to use 'noon' and 'midnight' instead. However, in everyday usage and in contexts where 24-hour time is not preferred, using 12 PM and 12 AM is generally acceptable and widely understood.