AM & PM Full Form

Know what does AM and PM Stand For?

Before understanding what AM and PM mean in the context of the 12-hour clock system, it is important to understand the 12-hour clock system first. The 12-hour clock system is a time convention used mainly in most of the analogue and digital clocks. This is a popular way to read time in most English-speaking nations and the then British colonies. The 12-hour clock convention is the one in which 24 hours are divided into two periods- AM and PM. 


Let us know what AM and PM mean in detail.


AM and PM are both Latin terms used to represent time in the 12-hour convention. A.M. stands for Ante Meridiem and P.M. stands for Post Meridiem. Meridiem is a Latin word that basically means midday (Meri means mid and Diem means day). Hence, Ante Meridiem means “before midday” and Post Meridiem means “after midday”. In the 12-hour clock system, AM and PM are used to before noon and after noon respectively. 


To understand this, you can simply look at it as two different time zones of 12 hours each that represent day and night. Basically, 24 hours are divided into two time zones (before noon and after noon) that last for 12 hours each.  The first 12-hour duration starts from midnight and lasts till noon which is called by AM (12 AM to 12 PM). The second 12-hour duration begins from noon and lasts till midnight denoted by PM (12 PM to 12 AM). 


Let us understand this with the help of examples. When someone says it's 9 AM, it means that the time is 9 O’ Clock in the morning. So, from 12 at night to 12 in the noon (exactly at 11:59 AM), it represents the day clock. Similarly, when someone says it is 9 PM, it means that the time is 9 O’ Clock in the evening. Hence, from 12 in the noon to 12 at midnight (precisely,11:59 PM), it is the night clock. 


These conventions are set up to understand time in a better manner. Suppose, if someone says that he/she will meet you at 8 O’ Clock tomorrow, it will be confusing whether that person meant 8 in the morning or 8 in the evening. To avoid such time-related confusion, the 24-hour daytime is divided into two different cycles of 12 hours each. Moreover, another confusion that is quite common is to understand 12 AM and 12 PM, also these are not technically correct. There is no such thing as 12 AM or 12 PM. It is actually called 12 in the noon (12 PM) and 12 at midnight (12 AM). To avoid the confusion, many companies including some airlines and banks, etc. use 12:01 AM to mark the beginning of an event that starts with the onset of the day and 11:59 PM to mark the end of any event that ends with the day. 


FAQ (Frequently Asked Questions)

Q1. How to convert 12-hour time format to 24-hour time format?

Ans: Converting 12-hour format to 24-hour format is fairly simple. The 24-hour clock is a time convention that runs from midnight to midnight, from hour 0 to hour 23. If the time is 12 AM (12 at midnight), it is simple 0:00 hours. Then, 1:00 AM is denoted as 1:00 hours and so on till 12 PM (12 in the noon) i.e. denoted as 12:00 hours. From 1:00 PM to 11:59 PM, add 12 hours. For example, if the time is 2:00 PM, you can say (2+12= 14) the time is 14:00 hours in 24-hour time format. 

Q2. Is 12 midnight AM or PM?

Ans: For many people, one of the most confusing things about time is to understand whether 12 midnight is AM or PM. Similarly, what is 12 at noon called? As per the convention, 12 AM denotes midnight and 12 PM denotes noon. However, to avoid confusion, it is better to use 12 noon and 12 midnight.