Do 午前 / 午後 change depending on minutes


午前0-12 goes from 00:00 to 12:00 in 24h time. Do minutes affect 午前 / 午後? Is
12:30 in 24h time still 午前１２時３０分 or does it change to 午後 thanks to the minutes
going over?




The most _technically correct_ answer would be... both 午前１２時３０分 and 午後１２時３０分
are nonexistent. Because if you apply 12-hour notation rigidly, the time range
only varies from 0:00 to 12:00 (whether the end is included or not is still
debatable). Hence the value `12:30 a.m/p.m` are simply not allowed.

That said, in daily life we could understand it by considering whether the
time belongs to morning (= before noon) or afternoon. In this sense, 12:30 in
24-hour notation would be 午後１２時３０分, if you have to use the number 12:30.

* * *

As I see from your comment, your concern is related to the controversy about
whether noon/midnight should have AM or PM. Basically [it depends on
definition](https://en.wikipedia.org/wiki/12-hour_clock#Confusion_at_noon_and_midnight),
but at any rate, the ambiguity only involves the very moment 12:00 AM/PM. If
the time should go past noon or midnight by a single tick, it'll automatically
fall under either AM or PM.

