I was thinking about this the other day so far google hasn’t given me a definate answer. Is 12 noon AM or PM?
PM
More specifically, the exact instant of noon is considered neither AM nor PM, according to Cecil. However, noon + 0.00…001 seconds is considered PM, so noon is normally considered to be PM as well, for convenience’s sake.
I think AP style guides tell people to write “noon” or “midnight” to avoid this problem.
According to this site noon is neither am nor pm.
The abbreviation “am” stands for “antemeridiem” or “before noon,” and the abbreviation “pm” stands for “postmeridiem” or “after noon.”
To be hypertechnical about it, therefore, the terms “12 am,” and “12 pm” have no meaning. Sorry, don’t have a cite, but I recall reading a stylebook that said that one should refer to “12 noon,” and “12 midnight.”
Despite all the technically correct explanations, there are conventions for practical purposes, especially for automation equipment such as computers.
12 noon is written 12:00 pm.
12 midnight is written 12:00 am.
Stylistically I often see the am/pm written as smaller sized capitals.
When my digital clock says “12:00”, the event of “noon” has already happened, and at that point it’s PM. Many times people will write “12 noon” but if you see “12:00 PM” written, it’s universally referring to noon.
Universally? Hardly. It’s been a point of confusion for decades.
Is zero a positive or negative number>
As soon as the second hand ticks past the “12,” yes, it is “PM” (or, if this is the middle of the night, “AM”). But in references to the hours of the day, it is “12:00 noon” (or “12:00 midnight”). No AM or PM. Just because it’s popular to say “12:00 PM” for “noon” doesn’t mean that it’s correct.
Of course, you could avoid the whole issue by using a 24 hour clock.
Thereby replacing it with the issue as to whether midnight is 0:00 or 24:00.
This site says it is both. There again, that site says you can convert 12 hour times to 24 hour times by adding 12 to PM times. So, 12:30 PM plus 12 = …
The beginning of the answer to Are noon and midnight 12 a.m. or 12 p.m.? from the National Instidute of Standards time FAQ: