How to read 24-hour clock format

Question

There are a lot of topics on forums in what case Japanese people use 24-hour clock format. But I have never seen how it should be pronounced. It's not hard to say something like 8:05. This is common and sounds like 「はちじ ごふん」, but how will it be if I want to read 15:40 or 19:20 etc. I didn't hear anything like 「じゅうごじ　よんじゅっぷん」 and I'm confused how it should be read.

Is it usual for Japanese people to translate 24 format into 12, or are there any edge cases they would use 24 strictly?

Answer 1

You can read the time of day in 24-hour format using the pronunciation for the numbers 13–24 as for the numbers 1–10 followed by 時【じ】, e.g.

15:40 = 15時40分 = じゅうごじ よんじゅっぷん
19:20 = 19時20分 = じゅうくじ にじゅっぷん

In particular, exceptions to the usual readings are the same

4時 = よじ　 → 14時 = じゅうよじ, 　24時 = にじゅうよじ
7時 = しちじ → 17時 = じゅうしちじ
9時 = くじ　 → 19時 = じゅうくじ

The same applies for higher numbers, e.g.

34時間 = さんじゅうよじかん.

For 0 you use 零【れい】, so

0:15 = 0時15分 = れいじじゅうごふん