We know that a day consists of 24hours. There are two different ways to calculate time - as 12 hours and as 24 hours. While using the 12 hour format, it is important to denote the time as p.m. or a.m. where A.M. stands for after Ante - meridian and is used before noon while P.M. stands for Post - Meridian and is used after noon.
Thus, from midnight till noon - we use A.M. while using the 12 hour format.
Whereas after noon till 11:59 in the night, we use P.M.
The 24hour format does not require these mentions. After 12 in the noon, instead of using 1:00 p.m. we use 13hours, 2:00 p.m. as 14:00 hours and so on. A 24 hour clock starts at 1:00 in midnight and ends at 23:59 hours.
The most simple way to convert 12 hours time format to 24 hours time format, follow these steps:
1. If the time is between 12:00 A.M. - 11:59 A.M. -- use the same time
2. if the time is between 12:00 P.M. - 11:59 P.M. -- add 12 to the time.
for example- 1:00 P.M. = 1+12 = 13:00 hours
6:30 P.M. = 6+12= 18:30 hours
I hope this helps.