Translation guide
The English word 'when' is used to ask about time, to indicate a point in time, or to describe a condition. In Japanese, the equivalent depends on the grammatical role: question word, subordinate conjunction, or conditional. This guide covers the most common and natural ways to express these functions.
The speaker wants to know the time of an event.
The standard question word for 'when'. Can be used in direct questions or embedded questions. Often followed by particles like に, から, まで for more specific time references.
いつ来ますか。
When will you come?
誕生日はいつですか。
When is your birthday?
いつから日本語を勉強していますか。
Since when have you been studying Japanese?
The speaker describes an action or state that occurs at the same time as another event.
The most common way to say 'when' in subordinate clauses. Attach to the plain form of verbs, adjectives, or nouns. The tense of the verb before とき indicates whether the action is completed or not relative to the main clause. For nouns and na-adjectives, use な before とき.
日本に行ったとき、富士山を見ました。
When I went to Japan, I saw Mt. Fuji.
The speaker describes a general truth or habitual action that occurs under a certain condition.
Used with the dictionary form of verbs and adjectives to express a natural consequence or habitual result. It implies that whenever the condition is met, the result inevitably follows. Cannot be used with volitional expressions (commands, requests, intentions) in the main clause.
春になると、桜が咲きます。
When spring comes, cherry blossoms bloom.
The speaker refers to a time as the object or subject of a sentence, like 'the time when...'
The same とき pattern can be used to create a noun phrase meaning 'the time when...'. It can be followed by particles like が, を, に, etc.
彼が来たときは、もう遅かった。
The time when he came was already late.
The speaker embeds a question about time within a statement.
Use いつ followed by a clause and か to form an embedded question. The clause after いつ is in plain form.
彼がいつ来るか知っていますか。
Do you know when he will come?
いつ始まるか教えてください。
Please tell me when it starts.
The speaker indicates the starting point of a continuous state or action.
Used after the te-form of a verb to mean 'since' or 'after' doing something. It emphasizes the sequence of actions and the state after that point.
日本に来てから、ずっと忙しい。
Ever since I came to Japan, I've been busy.
食べてから、お腹が痛い。
My stomach has been hurting since I ate.
The speaker describes a repeated action or state that occurs each time a condition is met.
Attaches to the dictionary form of verbs or noun + の to mean 'every time'. Emphasizes the repetition.
彼女に会うたびに、ドキドキする。
Every time I see her, my heart pounds.
The speaker expresses that something is true regardless of the time.
Means 'anytime' or 'whenever'. Can be used as a standalone adverb or in a clause.
These three patterns can all translate to 'when', but they have different nuances. とき simply indicates the time of an action. たら implies a specific condition or a one-time event, often with a sense of 'after' or 'if'. と expresses a natural, inevitable consequence or habitual action. Use とき for neutral temporal clauses, たら for specific or hypothetical situations, and と for general truths.
家に帰ったとき、電話が鳴った。
When I got home, the phone rang. (just stating the time)
家に帰ったら、電話が鳴った。
When I got home, the phone rang. (emphasizing the sequence or unexpectedness)
いつ着きましたか。
When did you arrive?
家に着いたら電話して。
Call me when you get home.
雨が降ると、屋根が漏る。
When it rains, the roof leaks.
What do you do when you are free?
子供のとき、よく公園で遊びました。
When I was a child, I often played in the park.
A more formal equivalent of とき. Used in written language or formal speech. Attaches to the plain form of verbs and adjectives, or noun + の.
お越しの際に、お電話ください。
When you come, please call us.
緊急の際には、このボタンを押してください。
In case of emergency (when it is urgent), please press this button.
When you press this button, the door opens.
A conditional form that can also mean 'when' for a specific one-time event or a general condition. More colloquial than と and can be used with volitional expressions. Formed by adding ら to the past tense plain form.
家に帰ったら、手を洗います。
When I get home, I wash my hands.
雨が降ったら、試合は中止です。
If/When it rains, the game will be cancelled.
A conditional form that can sometimes be translated as 'when' for general conditions, but it often carries a nuance of 'if'. Less common for pure temporal 'when' than と or たら. Formed by changing the last kana to the え-row and adding ば.
春になれば、花が咲く。
When spring comes, flowers bloom.
Do you remember the time when the earthquake happened?
Formal version of とき used in noun phrases. Often used in set phrases like この際 (on this occasion) or その際 (at that time).
お申し込みの際は、こちらのフォームをご利用ください。
When applying (at the time of application), please use this form.
Use this pattern to express 'whether or not' regarding time. いつ is followed by a clause and かどうか.
彼がいつ来るかどうか分かりません。
I don't know whether or not he will come (when he will come).
A more formal and emphatic way to say 'ever since'. Used with te-form. Often implies a long duration.
卒業して以来、彼に会っていない。
I haven't seen him since we graduated.
Whenever I travel, I buy souvenirs.
Attaches to nouns or dictionary form of verbs to mean 'every time' or 'each time'. Often used for regular intervals.
会う人ごとに挨拶する。
He greets every person he meets (whenever he meets someone).
一雨ごとに暖かくなる。
It gets warmer with each rainfall (whenever it rains).
Please come whenever you like.
彼はいつでも忙しい。
He is always busy (no matter when).
A pattern meaning 'no matter when' or 'whenever'. いつ is followed by a te-form verb + も.
いつ来ても、歓迎します。
Whenever you come, you are welcome.
いつ見ても、美しい。
It's beautiful no matter when you look at it.
家に帰ると、いつも電話が鳴る。
Whenever I get home, the phone rings. (habitual)
In English, 'when' can be both a question word and a conjunction. In Japanese, いつ is only a question word. To connect clauses, you must use patterns like とき, たら, と, etc. Using いつ alone in a subordinate clause is incorrect.
✕ いつ日本に行った、富士山を見た。
Intended: When I went to Japan, I saw Mt. Fuji.
◯ 日本に行ったとき、富士山を見た。
When I went to Japan, I saw Mt. Fuji.
The tense of the verb before とき is relative to the main clause. Use past tense before とき if the action is completed before the main action. Use non-past if the action is not completed or simultaneous.
日本に行くとき、カメラを買った。
I bought a camera when I was going to Japan (before leaving).
日本に行ったとき、カメラを買った。
I bought a camera when I went to Japan (after arriving).
I was happy when I heard the news.
家に帰ると、いつも電話が鳴る。
Whenever I get home, the phone rings. (habitual)
In English, 'when' can be both a question word and a conjunction. In Japanese, いつ is only a question word. To connect clauses, you must use patterns like とき, たら, と, etc. Using いつ alone in a subordinate clause is incorrect.
✕ いつ日本に行った、富士山を見た。
Intended: When I went to Japan, I saw Mt. Fuji.
◯ 日本に行ったとき、富士山を見た。
When I went to Japan, I saw Mt. Fuji.
The tense of the verb before とき is relative to the main clause. Use past tense before とき if the action is completed before the main action. Use non-past if the action is not completed or simultaneous.
日本に行くとき、カメラを買った。
I bought a camera when I was going to Japan (before leaving).
日本に行ったとき、カメラを買った。
I bought a camera when I went to Japan (after arriving).