Translation guide
The English word 'probable' is used to express that something is likely to happen or be true. In Japanese, this concept is most naturally expressed through sentence-ending expressions, adverbs, and adjectives that indicate likelihood or certainty. The choice depends on the level of certainty, formality, and whether it's based on evidence or intuition.
Express that something is probable or likely, without strong evidence or formal reasoning.
The most common and neutral way to say 'probably' in casual to semi-formal contexts. Attach to the plain form of verbs, adjectives, or nouns. Often used when the speaker is fairly confident based on intuition or general knowledge.
明日は雨が降るだろう。
It will probably rain tomorrow.
He has probably arrived home by now.
The polite version of 〜だろう. Used in formal speech, writing, and polite conversation. Slightly softer and more tentative than 〜だろう.
明日は雨が降るでしょう。
It will probably rain tomorrow. (polite)
この問題は難しいでしょう。
This problem is probably difficult.
An adverb meaning 'probably' or 'maybe'. Often used with 〜だろう/でしょう, but can stand alone in casual speech. Indicates a moderate level of certainty.
多分、彼は来ないだろう。
He probably won't come.
多分、大丈夫です。
It's probably okay.
A more formal and written-style adverb meaning 'probably' or 'likely'. Often used in news, reports, or formal speech. Implies a higher degree of likelihood based on reasoning.
恐らく、この計画は成功するだろう。
This plan will probably succeed.
Express that something is very likely or almost certain, often based on observable evidence or logical deduction.
Indicates strong conviction that something is true. 'Must be' or 'no doubt'. Used when the speaker is quite certain based on evidence or reasoning.
彼は疲れているに違いない。
He must be tired. (I'm sure he is.)
あの建物は図書館に違いない。
That building must be the library.
Expresses expectation based on reason or prior knowledge. 'Should be' or 'ought to be'. The speaker believes something is probable because of logical reasoning.
彼はもう着くはずだ。
He should arrive soon. (Based on the schedule.)
この薬を飲めば治るはずです。
If you take this medicine, you should get better.
Formal and literary equivalent of 〜に違いない. Used in written language or very formal speech. 'There is no doubt that...'
この文書は本物に相違ない。
This document must be authentic.
Express that something appears likely or seems probable based on what you see or hear.
Attach to verb stem or adjective stem to mean 'looks like' or 'seems like'. Used for immediate impressions based on appearance or situation.
Casual expression meaning 'seems like' or 'looks like'. Similar to 〜そうだ but more colloquial and can be used with nouns and full sentences.
彼は怒っているみたいだ。
He seems angry.
Slightly more formal than 〜みたいだ. Used for conjecture based on sensory evidence or situation.
誰か来たようだ。
It seems someone has come.
Express probability in academic, scientific, or formal written Japanese.
Literally 'the probability is high'. Used in technical or statistical contexts to say something is probable.
この治療法で治る確率が高い。
The probability of recovery with this treatment is high.
Means 'the possibility is high' or 'highly likely'. Common in news and formal writing.
地震が発生する可能性が高い。
There is a high probability of an earthquake occurring.
だろう/でしょう are general 'probably'. はずだ is 'should be' based on reason. に違いない is 'must be' with strong conviction. Use でしょう in polite contexts, だろう in casual. はずだ implies logical expectation, while に違いない is more intuitive certainty.
彼は来るだろう。
He'll probably come. (general guess)
彼は来るはずだ。
He should come. (because he promised)
彼は来るに違いない。
He must be coming. (I'm sure of it)
While 多分 (tabun) is a direct translation of 'probably', Japanese often embeds probability in the verb ending (〜だろう/でしょう) without an adverb. Using 多分 in every sentence can sound unnatural. Let the sentence ending carry the nuance.
明日は雨が降るでしょう。
It will probably rain tomorrow. (natural without 多分)