Like a lot of other foreign guys, I picked up some of my Japanese from imitating the women I spoke to. Certain phrases may have made me sound unwittingly effeminate in the early days when I had less of a grasp on the nuances.

One of those habits was to use でしょう at the end of sentences, to express uncertainty, asking confirmation, or wondering aloud.

Later on I was told that it was more masculine to use だろう. Even though that was years ago, I never really got comfortable with だろう. I'm not sure I'm using it right, and it feels weird saying it.

First, is だろう really the more masculine form of でしょう? It seems sometimes I do hear men use でしょう, and women use だろう. Do they mean different things?

Second, are だろ and だろう different?

Lastly, what is the difference between these two statements:



  • 3
    It is ironical that you are using the linguistic term 'diphthong'. Actually, Japanese does not have a diphtong, and what you are mentioning as it is a long vowel.
    – user458
    Jul 19, 2011 at 6:51
  • 3
    Just for your reference. Diphthong is not "two adjacent vowel sounds occurring within the same syllable", but is "two different adjacent vowel sounds occurring within the same syllable", .
    – user458
    Jul 19, 2011 at 13:05
  • For completeness: だろう and でしょう are conjugations of だ and です respectively, and have the same relationship to each other. Aug 3, 2022 at 4:46

2 Answers 2


Note: I'm going to try to do this without using technical terminology. If I start being too technical, let me know and I'm more than willing to revise!

Okay, let's get a few things out of the way. As you know, there is a scale of informal ⇔ formal in Japanese grammar. It is very similar to the scale of impolite ⇔ polite, but politeness is generally dependent on context.

So what does this mean for だろう and でしょう? Basically, the former is informal, the latter formal. If that's the only difference, why is だろう often considered "more masculine"? I would say that it has to do with what kind of language you're using in what kind of context. My overbroad generalization of the situation is represented by this table (where L is the kind of language used and C is the context):

            Informal-L  Formal-L
Informal-C  Masculine   Feminine
Formal-C    Impolite    Polite

[Note: if anybody knows a better way to format a table, please let me know.]

Culturally and historically speaking, "feminine" speech is generally more formal (though there are certainly other features), while "masculine" speech is more informal (consider 俺、僕、私 and where each falls on the scales of formality and gender). So because だろう is less formal, it may be considered more masculine; likewise, because でしょう is more formal, it may be considered more feminine -- but mostly, it's about context. Using でしょう with your teacher or boss is not feminine. Using it with your friends may be.

So that's the answer to the first part of your question! Now let's move on to the third part. I'll come back to the second in a moment. You ask about the differences between these two sentences:

  • 何かあったのだろうか。
  • 何かあったと思う。

They are actually quite different. To answer, however, we'll need to analyze a third:

  • 何かあったのだろう。

But wait! Aren't ~だろう and ~だろうか the same thing? The answer: no. The first is for confirmation ("Something happened, right?") or conjecture ("Something probably happened."), while by attaching か it becomes either a question ("Did something happen?") or wondering ("I wonder if something happened.").

~と思う, on the other hand, is simply used to express what one thinks. It contains conviction: "I think something happened," while ~だろう(か) is much more uncertain.

[Edit: Derek Schaab pointed out in the comments that this is a less than satisfactory explanation. Allow me to try again. Here goes...]

~と思う, on the other hand, offers one's thoughts. When you say ~と思う, you believe what you are saying; the same is not necessarily true for だろう (though it may be much of the time). It's difficult to compare to these two because 思う is for thoughts and だろう is more for guesses. ~と思う is always subjective, but subjectivity isn't an issue with だろう: it can range from completely subjective to based in solid fact.

Now that we have this out of the way, what is the difference between だろ and だろう? First of all, だろ is even more informal than だろう. But more importantly, I do not believe it can be used with か, though I may be wrong.

As for the actual difference in sound, the difference is that だろ is two morae, and だろう is three. Basically that means that だろ is the same length as みず, but in だろう, the "o" sound is twice as long, making it as long as みずが. The traits of short and long vowels in Japanese could be a question in its own right, however.

  • Excellently explained. I do wonder about your statement regarding the relative level of conviction between ~と思う and ~だろう, however. It feels to me like the former is subjective ("I think…") while the latter is more objective ("[Looking at the situation,] it's likely that…"). Could you elaborate on this particular point? Jul 20, 2011 at 21:29
  • @Derek I've edited my answer and tried to explain the difference more clearly. Not quite sure how well I did, though. :p
    – rintaun
    Jul 20, 2011 at 22:10
  • Yes, I think this covers the difference better, and more completely than I suggested, since you are correct in that ~だろう can be subjective as well as objective. Jul 20, 2011 at 23:13
  • @rintaun: I believe the new segment works very well, excellent job on this answer. I have seen that だろか does exist, but it is extremely informal and rather childish/slangish. Jul 20, 2011 at 23:24

It's late so I'll keep this fairly short and make edits if need-be later.

It's not that だろう is more masculine in form, it is that it is less formal. And to be less formal, is to be more masculine.

While slowly changing, Japanese speech is still, for lack of a better word, sexist (as well as many other languages, English included). Therefore it is more manly to speak in a more blunt, and less formal tone.

だろ is a shortening of だろう, which is itself a shortening and so on. Think of them as the same, as the diphthong, in this case, is more of a pronunciation thing. Although, once again, more masculine is shorter and blunter, therefore だろ is technically manlier.

でしょう is the polite form of the same expression, just to clarify.

The Difference between だろう and と思う:

There are many nuances, so I will just state the major points. だろう is an assertion, it means, I feel this way, you should to. Much similar to the よ (だよ) particle. But よ is a bit more forceful saying, this is how it is, I'm telling you.

On the other side is と思う. と思う means to think, while not entirely knowing. It is one of the more humble ways to make a statement, since it distances you from your views as they are merely incomplete thoughts.


This phrase to loosely translate would mean, "I think something happened, right?" It is in essence asking if you are correct in your owns assertions. With a larger tone of, I think I'm right. In order to get a higher contrast with the next phrase, I'll use the translation of "Something had to have happened, right?"


This phrase loosely translates to "I think something happened." Notice how it is not imposing on the listener. It is simply a statement of thought, whereas the former statement seeks agreement.

  • 3
    だろう is not an assertion. The usage meaning 'I feel this way, you should too' is different from the usage in question. Also, expresses expectation that the addressee does not know or does not agree, contrary to what you say. Your translation for 何かあったのだろうか is entirely wrong.
    – user458
    Jul 19, 2011 at 7:00
  • 2
    @sawa: I agree that formal and polite are different things, but I would not say だろう is more formal than でしょう. The reason だろう is much more common than でしょう in academic papers is that academic papers are written with 常体 (だ・である調) instead of 敬体 (です・ます調), but that does not mean that 常体 is more formal than 敬体. Jul 19, 2011 at 15:55
  • 1
    @Tsuyoshi_Ito You are right. And furthermore, だろう is at least less formal than であろう because it is a contracted form of the latter. I will remove my first comment.
    – user458
    Jul 19, 2011 at 23:09
  • 2
    @Greg 1. If you are analyzing だろう back into the form before contraction であろう and further into de ar + ou, then, you can say that the de ar part is assertion. But you don't seem to be doing that. だろう as a whole is weaker than assertion. It expresses presumption. 2. The meaning 'I feel this way, you should too' is possible when you are pronouncing だろう with a rising tone, as if the sentence is a question. That is not the usage in だろうか. 3. For , it is just as I said in the comment above. The sentence-final particle sounds like what you describe.
    – user458
    Jul 21, 2011 at 0:00
  • 1
    @Greg 4. 何かあったのだろうか is expressing that you are wondering whether something happened. It does not mean 'I think something happened'. Nor does it mean that you are expecting agreement from the addressee like right?. If you are taking this sentence as a rethorical question, then it would rather mean the opposite of what you say: 'Did anything (ever) happen? (I expect not)'.
    – user458
    Jul 21, 2011 at 0:02

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