How to tell them apart
際（に） marks a formal, special occasion and sounds stiff in everyday speech, while 時・とき is the general word for any time or moment. Use 際（に） for ceremonies, important opportunities, or set phrases like この際; use 時・とき for routine events like 食べる時 or 寝る時. Swapping them feels odd: 卒業の際に is natural, but 朝ごはんを食べる際に sounds overly formal.
- 際（に） Use 際（に） for formal or special occasions like graduations, ceremonies, or important opportunities.
- 時・とき Use 時・とき for ordinary, everyday timing without any special or formal nuance.
| Grammar point | Meaning | JLPT level |
|---|---|---|
| 際（に） ni | at the time of, on the occasion of (formal usage) | N3 |
| 時・とき toki | at the moment when; during the period of | N5 |
際（に） ni
at the time of, on the occasion of (formal usage)
際（に）means 'when' or 'on the occasion of' and is used in formal, written, or official contexts. It attaches to plain-form verbs or to nouns with の, as in 出火の際. It can also appear as この際 to mean 'at this point, once and for all'.
-
出火の際は、すぐに１１９番に電話しなければならない。
In case of fire, you should dial 119 immediately.
-
海外へ旅行する際には、通常、パスポートが必要である。
When you travel abroad, you usually need a passport.
時・とき toki
at the moment when; during the period of
時 (とき) marks the time when something happens or a period in someone's life. It follows a noun directly, as in 高1の時, and can also follow clauses describing the situation, as in つらいとき. It works in both casual and polite speech.
-
何時くらいまでなら電話してもいいですか。
How late can I ring?
-
１１時になっているよ。
It is already eleven.
際（に） and 時・とき are JLPT N5–N3 grammar points that Japanese learners often mix up. This page compares them side by side on meanings, usage and example sentences, so you can tell them apart.