Important Words to Know…
Asking for time in Japanese is as simple as asking:
今何時ですか？Ima nan ji desu ka?
What time is it now?
Understanding or giving the answer is a bit trickier.
First of all, it is imperative to learn the different time-related expressions. If you’re already familiar with Japanese numbers, it should be fairly easy to memorize.
1：一時：いちじ：ichi ji (one o’clock)
2：二時：にじ：ni ji (two o’clock)
3：さんじ：san ji (…)
11：十一時：じゅういちじ：juu ichi ji
12：十二時：じゅうにじ：juu ni ji
1: 一分：いっぷん：ippun (one minute)
2:二分：にふん：ni fun (two minutes)
3:三分：さんぷん：san pun (…)
15:十五分：じゅうごふん：juu go fun
There are a few things, a few distinctions which are important to keep in mind however.
Minute (分) has two different ways of being pronounced. It can either be pronounced ふん (fun) or ぷん(pun), depending on the numeral it is used with.
If used with the numbers 2, 5, 7 or 9, minute is pronounced ふん (fun)。
If used with the numbers 1, 3, 4, 6, 8 and 10, minute is pronounced ぷん (pun)。
Although four is pronounced よ (yo) when referring to the hour (o’clock), it is pronounced よん (yon) when referring to the minute.
When referring to half an hour, the term はん(han) is used, which means “half”. It is also possible to say thirty minutes: さんじゅうっぷん (san juu ppun) but is longer and less common.
Giving the Time in Japanese
You now know how to ask the time in Japanese. What about giving it however?
When giving the time in Japanese, first of all, you can repeat ima wa (which means now) followed by the actual time.
If someone asks you for the time, you won’t probably have to mention whether it’s in the morning or in the afternoon as it’ll be obvious from the context. On the other hand, if you’re making an appointment, specifying whether it will be in the morning or in the afternoon can sometimes be required.
In case you need to precise whether it’s in the morning or in the afternoon:
午前：ごぜん：gozen: means in the morning.
午後：ごご：gogo : means in the afternoon.
If required, specify whether it is in the morning or in the afternoon right after “ima wa”, which means “now”.
Let’s look at a quick example.
A Japanese friend is calling you in America. He wants to know what time it is in your country. So he asks you the usual:
今何時ですか？Ima nan ji desu ka? (what time is it now?)
It’s 4:30 in the afternoon.
Look up four o’clock in the previous chart.
Four o’clock in Japanese is: よじ（四時）.
Now look up how to say 30 minutes in Japanese…
Remember to put whether it’s in the morning or in the afternoon right after “ima wa” in your answer.
So your answer is:
Ima wa gogo yo ji han.
今はごぜん四時半です。(ima wa gogo yo ji han desu).
You may also find Using Japanese Numbers and Telling Time useful.