Translation guide
In Japanese, expressing modality—such as possibility, necessity, obligation, permission, volition, or evidentiality—relies on a range of auxiliary verbs, adjectives, sentence-ending particles, and adverbial phrases. The choice depends on the specific modal meaning and the level of formality.
Expressing that something can or cannot be done, or that a situation is possible.
The potential form of verbs or the construction 'Vことができる' expresses ability or possibility. The potential form is more common in casual speech, while 'ことができる' is slightly more formal.
日本語が話せる。
I can speak Japanese.
ここで泳ぐことができる。
You can swim here.
Combines potential with uncertainty, meaning 'might be able to'. Used when the possibility is not certain.
明日は来られるかもしれない。
I might be able to come tomorrow.
A formal/literary expression meaning 'possible' or 'can happen'. Often used in written language.
それはあり得ることだ。
That is a possible thing.
Expressing that something must be done or is necessary.
The standard way to express 'must' or 'have to'. 'なければならない' is slightly more formal than 'なければいけない', but both are common.
宿題をしなければならない。
I have to do my homework.
もう行かなければいけない。
I must go now.
More casual versions. 'なくちゃ' is a contraction used in informal speech.
早く起きなくちゃ。
I have to wake up early.
Literally 'there is a necessity', used to express need in a more formal or objective way.
詳しく調べる必要がある。
It is necessary to investigate in detail.
Expressing that something is allowed or forbidden.
The most common way to ask for or give permission: 'You may do ~' or 'Is it okay if I ~?'.
ここに座ってもいいですか。
May I sit here?
食べてもいいよ。
You can eat it.
Expresses prohibition: 'must not' or 'cannot'. 'だめ' is more casual and direct.
ここで写真を撮ってはいけません。
You must not take photos here.
遅れちゃだめだよ。
Don't be late.
Expresses lack of obligation: 'don't have to'. Note the difference from prohibition.
明日は来なくてもいいです。
You don't have to come tomorrow.
Expressing one's will, intention, or invitation to do something.
Expresses the speaker's intention: 'I think I will ~' or 'I'm planning to ~'.
日本に行こうと思う。
I'm thinking of going to Japan.
The volitional form used for invitations or offers: 'Let's ~' or 'Shall I ~?'. 'ましょう' is the polite form.
A noun used after the dictionary form of a verb to express a firm intention or plan: 'intend to'.
Expressing that information is based on hearsay, observation, or inference.
Expresses hearsay: 'I heard that ~' or 'They say that ~'. The information source is someone else.
明日は雨が降るそうだ。
I heard it will rain tomorrow.
Expresses conjecture based on direct observation: 'It looks like ~' or 'Seems ~'. Note the different conjugation from hearsay.
雨が降りそうだ。
It looks like it's going to rain.
Expresses conjecture based on reliable information or situation: 'It seems that ~' or 'Apparently ~'.
彼は来ないらしい。
Apparently he's not coming.
More casual than 'らしい', used for conjecture based on direct evidence or similarity.
誰か来たみたいだ。
It seems someone came.
Expressing that it would be good to do something, or giving advice.
Used to give advice: 'You should ~' or 'It's better to ~'. The past tense form is used even for future actions.
早く寝たほうがいいよ。
You should go to bed early.
Expresses strong advice or moral obligation: 'ought to' or 'should'. More formal and emphatic than 'ほうがいい'.
もっと勉強するべきだ。
You should study more.
Expressing degrees of certainty about a statement.
Expresses conjecture or probability: 'probably' or 'I think'. 'でしょう' is the polite form.
明日は晴れるだろう。
It will probably be sunny tomorrow.
Expresses uncertainty: 'might' or 'maybe'. Indicates a lower probability than 'だろう'.
彼は来ないかもしれない。
He might not come.
Expresses strong conviction: 'must be' or 'no doubt'. More certain than 'だろう'.
彼は成功するに違いない。
He must succeed.
Expresses expectation based on reasoning: 'should' or 'ought to'. Implies the speaker has a logical basis.
彼はもう着いたはずだ。
He should have arrived by now.
Hearsay そうだ attaches to the plain form of verbs/adjectives (e.g., 降るそうだ 'I heard it rains'), while conjecture そうだ attaches to the stem of verbs or adjective stems (e.g., 降りそうだ 'It looks like it will rain'). Pay attention to the conjugation.
English 'must' is not directly translatable as a single word. Use the double negative constructions like 〜なければならない or 〜なくてはいけない. Using 〜なければ alone is incomplete.
I intend to get married next year.