Comparing 午前 and 午後 with A.M. and P.M.
Quick: Is Noon 12 a.m. or 12 p.m.?
The 12-hour notation using A.M. and P.M. is common in many parts of the English speaking world. One o’clock through eleven o’clock in the morning is written as 1 a.m., 2 a.m., etc. And one o’clock through eleven o’clock in the evening is written as 1 p.m., 2 p.m., etc.
But Midnight is 12 a.m. and Noon is 12 p.m. Most English speakers simply have this memorized, but for those of us who have trouble keeping this straight, Wikipedia's entry on this subject has this bit of advice:
“In the United States, noon is often called ‘12:00 p.m.’ and midnight ‘12:00 a.m.’. With this convention, thinking of ‘12’ as ‘0’ makes the system completely logical.”
With that in mind (midnight=0 a.m.), the Japanese way of counting time is easier to understand.
From zero o’clock (midnight) to eleven o’clock in the morning we write
Government offices or insurance companies in Japan write time this way with Midnight being 午前０時 and noon being 午前１２時.