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.
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.
It will probably rain tomorrow. (polite)
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.
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.
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.
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.
Express probability in academic, scientific, or formal written Japanese.
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.
He'll probably come. (general guess)
It is probable that he forgot.
Using のだろう adds explanatory tone
This problem is probably difficult.
多分、彼は来ないだろう。
He probably won't come.
It's probably okay.
恐らく、この計画は成功するだろう。
This plan will probably succeed.
He must be tired. (I'm sure he is.)
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.
He should arrive soon. (Based on the schedule.)
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...'
This document must be authentic.
It looks like it's going to rain.
He seems energetic.
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.
He seems angry.
Slightly more formal than 〜みたいだ. Used for conjecture based on sensory evidence or situation.
It seems someone has come.
The probability of recovery with this treatment is high.
Means 'the possibility is high' or 'highly likely'. Common in news and formal writing.
There is a high probability of an earthquake occurring.
彼は来るはずだ。
He should come. (because he promised)
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.
It will probably rain tomorrow. (natural without 多分)
Success is probable.
Formal/technical