How to tell them apart
The core contrast is certainty level: でしょう/だろう expresses a confident guess with moderate probability, while かもしれない expresses genuine uncertainty, acknowledging a real possibility that could go either way. Swapping them feels off because かもしれない downplays what you're fairly sure of, and でしょう overstates what you're unsure about. For instance, 雨が降るでしょう sounds like a weather forecast, whereas 雨が降るかもしれない sounds like a mere possibility.
- だろう Use でしょう/だろう when you lean toward a likely outcome without hard evidence.
- かもしれない Use かもしれない when you genuinely can't tell and want to flag a real possibility.
| Grammar point | Meaning | JLPT level |
|---|---|---|
| だろう darou | Likely so; I suppose | N4 |
| かもしれない kamoshirenai | might; possibly; perhaps | N4 |
だろう darou
Likely so; I suppose
だろう expresses the speaker's conjecture, adding a 'probably' or 'I suppose' tone to a statement or exclamation. It follows the plain form of verbs and i-adjectives, and noun or na-adjective stems, and is the casual counterpart of でしょう.
-
下着を買いに行くんだよ。お前、まだノーパンだろうが。
We're going to buy underwear. You're still not wearing underpants, are you?
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10ヶ国語を話せたらどんなにかっこいいだろう！
It would be so cool if I could speak ten languages!
かもしれない kamoshirenai
might; possibly; perhaps
かもしれない expresses that something is possible but uncertain, like English
-
明日雨になるかもしれないがともかく私たちは出かけるつもりだ。
It may rain tomorrow, but we are going in any case.
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夜には雨になるかもしれない。
It may rain in the evening.
だろう and かもしれない are both JLPT N4 grammar points that Japanese learners often mix up. This page compares them side by side on meanings, usage and example sentences, so you can tell them apart.