だろうdarou“probably or right?”

だろう is the plain (casual) form of でしょう. You attach it to the end of a sentence to say “probably”, or, with a rising voice, to ask “…right?”. It is JLPT N5 grammar, but it behaves a little differently from its polite partner, so it is worth learning on its own.

だろう = your own guess, in plain style. Say it flat and it means "probably". Raise your voice at the end and it means "right?".

What does だろう mean?

だろう turns a statement into a guess. 雨が降る means “it will rain”. 雨が降るだろう means “it will probably rain”. The speaker is not reporting a fact. They are giving their own prediction, based on what they know or can see.

It has two main jobs:

• Guess / prediction (falling intonation): 明日は寒いだろう。 — It will probably be cold tomorrow.
• Checking with the listener (rising intonation, often written with ？): これ、君のだろう？ — This is yours, right?

In the second job, the speaker is fairly sure and wants the listener to agree. English “right?”, “isn’t it?” or “you know” fits well here.

How to form だろう

だろう comes after plain forms. The one rule that trips people up: nouns and な-adjectives drop だ and take だろう directly.

Quick attachment chart:

• Verb: 雨が降るだろう, 雨が降らないだろう, 雨が降っただろう
• い-adjective: 高いだろう, 高くないだろう
• な-adjective: 静かだろう (not 静かなだろう, not 静かだだろう)
• Noun: 学生だろう, 学生だっただろう

Never put だろう after a ます form. 行きますだろう is wrong. If you want a polite version, switch the whole ending to 行くでしょう.

When is だろう used?

You meet だろう in three places.

Writing and narration. Newspapers, essays, textbooks and novels use だろう as the neutral way to predict. A news article might say 来年は物価が上がるだろう (“prices will probably rise next year”). In writing, it is not rude or masculine at all. It is just plain style.

Casual speech between friends. Face to face, a bare だろう sounds direct and confident. It is used more by men, and it can sound rough when you say it to someone you do not know well. In conversation it is often shortened to だろ. Many speakers, especially women, prefer でしょ in the same slot.

After と思う. 〜だろうと思う (“I think it will probably…”) is very common in speech and sounds softer than a bare だろう. 試験は難しいだろうと思います is polite because the sentence ends in ます.

Adverbs that pair naturally with it: たぶん (probably) and きっと (surely). たぶん雨が降るだろう is a mild guess. きっと雨が降るだろう is a confident one.

だろう example sentences

Look at the form in front of だろう each time: 降る, いる, 高い, 静かじゃない, 行く, 楽しかった, 難しい. All of them are plain forms. Only the ending changes the sentence from a fact into a guess.

Nuance of だろう

It is your own judgement. だろう says “this is what I think is likely.” It is not hearsay. If a friend told you it will rain, and you are passing on that information, だろう is not the right tool. That job belongs to そうだ at N4.

It is not for your own plans. You know what you are going to do, so you cannot guess about it. 私は明日行くだろう sounds like you are predicting your own behaviour from the outside. For plans, say 明日行きます or 明日行くつもりです.

Intonation changes the meaning. Flat or falling だろう is a prediction. Rising だろう？ asks for agreement and assumes the answer is yes. Written Japanese shows the difference with 。 or ？.

Register depends on the medium. In print, だろう is neutral. In speech, a bare だろう to a teacher, boss or stranger sounds too blunt. Use でしょう there.

💡 Tip: If you hear だろ at the end of a line in anime or manga, it is almost always the "right?" meaning, often with a pushy or teasing tone.

だろう vs でしょう

These two mean the same thing. The difference is register, plus a few small usage points.

The attachment rules are identical: 静かでしょう, 学生でしょう, 行くでしょう. So once you know one, you know both. Choose by listener: friend or text, だろう. Anyone you would speak to with です and ます, でしょう. See the full lesson on でしょう.

Common mistakes with だろう

Is だろう on the JLPT?

A typical grammar item gives you 「あしたは　さむい（　）。」 with choices like だろう, です, ましょう, and asks which one makes a prediction. Another checks that you do not add な or ます before だろう.

Practice questions for だろう

Learning path for だろう

Related grammar to review next

• でしょう — the polite twin of だろう, with the same attachment rules and meaning
• ね — the other way to seek agreement, softer than a rising だろう？
• かもしれない — a weaker guess (“might”) that you will contrast with だろう at N4
• かな — the casual “I wonder…” that often replaces だろう when you talk to yourself
• と思う — the frame in だろうと思う, the most common spoken way to use this guess

Learn だろう with Hane

Hane drills だろう and でしょう side by side, so you learn to pick the ending that fits your listener. Start practicing with Hane.