Military time converter
Type a time in either format and you get all three readings. Military time is the 24-hour clock written without a colon, so 5:45 pm is 17:45 and 1745.
How to convert military time
One rule covers almost everything: after noon, add twelve to the hour. The exceptions are the two that catch everyone. Midnight is 12:00 am but 0000, and noon is 12:00 pm but 1200, so twelve is the one hour where the am/pm label and the number move in opposite directions. It is also why hospitals, airlines and the military use the 24-hour clock at all: there is no way to write an ambiguous midnight in it. Written properly, military time has four digits and no colon, and is often spoken with hundreds: 1700 is "seventeen hundred".
Questions
6:00 pm. Subtract twelve from any hour of 13 or more.
Both are used. 0000 starts the day and 2400 ends the previous one; they are the same instant. This tool writes 0000.
Because the 12-hour clock counts from twelve rather than zero, so the twelfth hour keeps the number while flipping the label. It is the single most confusing hour in the system.
Not traditionally; 1745, spoken as "seventeen forty-five". The 24-hour clock in civilian use writes 17:45.
It is required. Seven in the morning is 0700, and writing 700 is not valid military time.