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.
When (subordinate clause, past event)
Attach to plain form of verb/adjective. For past events, use past tense before とき.
When (conditional, general/habitual)
Use with dictionary form for natural consequences or habitual actions.
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.
When will you come?
When is your birthday?
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.
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.
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.
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.
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.
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.
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.
When did you arrive?
When I went to Japan, I saw Mt. Fuji.
What do you do when you are free?
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.
When you come, please call us.
In case of emergency (when it is urgent), please press this button.
When spring comes, cherry blossoms bloom.
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.
When I get home, I wash my hands.
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.
When spring comes, flowers bloom.
The time when he came was already late.
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).
When applying (at the time of application), please use this form.
Do you know when he will come?
Please tell me when it starts.
Use this pattern to express 'whether or not' regarding time. いつ is followed by a clause and かどうか.
I don't know whether or not he will come (when he will come).
Ever since I came to Japan, I've been busy.
My stomach has been hurting since I ate.
A more formal and emphatic way to say 'ever since'. Used with te-form. Often implies a long duration.
I haven't seen him since we graduated.
Every time I see her, my heart pounds.
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.
He greets every person he meets (whenever he meets someone).
It gets warmer with each rainfall (whenever it rains).
Please come whenever you like.
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.
Whenever you come, you are welcome.
It's beautiful no matter when you look at it.
When I got home, the phone rang. (just stating the time)
When I got home, the phone rang. (emphasizing the sequence or unexpectedness)
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.
Intended: When I went to Japan, I saw Mt. Fuji.
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.
I bought a camera when I was going to Japan (before leaving).
I bought a camera when I went to Japan (after arriving).
Call me when you get home.
When it rains, the roof leaks.
I was happy when I heard the news.