GrammarJLPT N5
→ seems
Conjecture, Supposition, and Seeking Agreement
JLPT N5Sentence-ending expressionNeutral
だろう is a sentence-ending expression used to express the speaker's conjecture or supposition about something ("it seems," "I think," "probably"), or to seek confirmation or agreement from the listener ("right?"). It attaches to the plain form of verbs, adjectives, and nouns. When expressing conjecture, だろう conveys a moderate level of certainty — the speaker believes something is likely but is not stating it as absolute fact. When used with rising intonation, it functions as a tag question seeking the listener's agreement, similar to English "right?" or "don't you think?" The polite equivalent is でしょう, which is used in formal or polite speech. While かもしれない expresses lower certainty ("might"), だろう suggests the speaker is fairly confident in their guess. Note that だろう is more commonly used by male speakers in casual conversation, while でしょう is used by all genders in both polite and casual speech (casual でしょう with rising intonation is common among female speakers).
Functions
#1 Expressing conjecture or supposition
Structure
Plain form + だろう
明日は雨が降るだろう。
Here だろう is used to express the speaker's supposition about tomorrow's weather. The speaker believes it is likely to rain but is not stating it as a confirmed fact. This is the most common use of だろう, equivalent to "probably" or "I think" in English. The verb 降る remains in its plain dictionary form before だろう is attached.It will probably rain tomorrow.
Structures
- Verb
- Verb (plain form) + だろう
- い-Adjective
- い-Adjective (plain form) + だろう
- な-Adjective
- な-Adjective (stem) + だろう
- Noun
- Noun + だろう
Common mistakes
A very common mistake is placing だ before だろう after nouns or な-adjectives, producing incorrect forms like 学生だだろう or 静かだだろう. The correct forms are 学生だろう and 静かだろう, because だろう itself already contains the conjectural form of the copula. Another frequent error is confusing だろう with かもしれない; while both express uncertainty, だろう indicates higher confidence ("probably") whereas かもしれない indicates possibility ("might"). Learners also sometimes use だろう in polite conversations where でしょう would be more appropriate, which can sound overly blunt or masculine. Finally, some learners forget that the confirmation-seeking use of だろう requires rising intonation; without it, the sentence sounds like a statement of conjecture rather than a question.
Related
でしょうかもしれないだろうと思うらしいと思うじゃないか