Expressing Certainty in Japanese || Levels of Certainty Explained

Q: How to use だろう ?

だろう da rou is an informal way to express certainty in Japanese. The formal way is でしょう de shou (formal). These two come at the end of a sentence and sound like “probably” or “right?”. だろう da rou is mostly used by men, so stick to the more polite version, でしょう deshou , if you’re a lady. You can use either of these with the dictionary form of a verb, or any nouns/adjectives. Examples: 明日は雨が降るだろうか。 Ashita wa ame ga furu darou ka. I wonder if it will rain tomorrow. -- 彼はきっと遅れてくるでしょう。 Kare wa kitto okurete kuru deshou. He will surely come late.

Q: How to use かもしれない ?

かもしれない (kamoshirenai ) translates to something like “maybe” in English and is stuck at the end of sentences without conjugation. It can be shortened to かも kamo too and has the same meaning. One very important thing to note is that often the direct translation for かもしれない kamoshirenai sentences is “maybe x”, but the true meaning might be stronger. Japanese people don’t often like to give strong opinions, so soften the blow with かもしれない kamoshirenai . Examples: 今日は雨が降るかもしれない。 Kyou wa ame ga furu kamoshirenai. It might rain today. -- 彼は忙しいかもしれません。 Kare wa isogashii kamoshiremasen. He might be busy.

Q: How to use はずだ ?

はずだ hazu da conveys a strong sense of assurance and can be interpreted as “expected to be” or “ought to.” This approach signifies that you arrive at conviction through objective analysis. When linking nouns and な na -adjectives, it’s essential to affix の no to nouns and な na to な na -adjectives, respectively. Examples: この店の料理は美味しいはずだ。 Kono mise no ryouri wa oishii hazu da. The food at this restaurant is supposed to be delicious. -- その計画は成功するはずだ。 Sono keikaku wa seikou suru hazu da. The plan is expected to succeed.

Q: Where can I study more Japanese grammar?

You should have a look at our Japanese Grammar Bank , where we regularly publish free lessons for levels A1, A2 and B1.

Q: Can I learn Japanese with LTL?

Yes, you can! We teach Japanese online, on our Flexi Classes platform. We can also organise a language program for you in Tokyo, where you can study in group or individual classes, as well as live with a Japanese family.

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CERTAINTY IN JAPANESE

Learning how to express different levels of certainty is an essential part of articulating yourself in any language.

With Japanese being especially nuanced, the importance of mastering this can’t be understated.

By the end of this article, you should be able to navigate this maze.

CERTAINTY IN JAPANESE WITH だろう & でしょう

だろう da rou (informal)
でしょう de shou (formal)

These two come at the end of a sentence and sound like “probably” or “right?”.

だろう is mostly used by men, so stick to the more polite version, でしょう, if you’re a lady.

You can use either of these with the dictionary form of a verb, or any nouns/adjectives.

These are used for things that are slightly more opinionated than when you use ね, which is used for generally accepted things.

PATTERN #1

Verb / Nouns / Adjectives + だろう

When this is used as a question, it expresses doubt and can often be paired with かな.

Examples with だろう:

japanese	romaji	english
この店の料理は美味しいだろう。	Kono mise no ryouri wa oishii darou.	The food at this restaurant is delicious.
明日は雨が降るだろうか。	Ashita wa ame ga furu darou ka.	I wonder if it will rain tomorrow.

View More Examples:

JAPANESE	ROMAJI	ENGLISH
今日は晴れるだろう。	Kyou wa hareru darou.	It will probably be sunny today. NOTE: Weather broadcasters will often use phrases like this.
彼の提案はうまくいくだろうと思います。	Kare no teian wa umaku iku darou to omoimasu.	I reckon his proposal will go well.
その花はきれいだろう。	Kono hana wa kirei darou.	I bet those flowers are beautiful.

PATTERN #2

Verb / Nouns / Adjectives + でしょう

Examples with でしょう:

JAPANESE	ROMAJI	ENGLISH
彼はきっと遅れてくるでしょう。	Kare wa kitto okurete kuru deshou.	He will surely come late.
あの映画は面白いでしょうね。	Ano eiga wa omoshiroi deshou ne.	That movie is interesting, don’t you think?

View More Examples:

Japanese	romaji
この問題は難しいでしょう。	Kono mondai wa muzukashii deshou.	This problem is difficult, right?!
あの場所には行ったことがないでしょう。	Ano basho ni wa itta koto ga nai deshou.	You probably haven’t been to that place.
そんなことはあり得ないでしょう！	Sonna koto wa arienai deshou!	That kind of thing is impossible, right?!

You can throw んだ or のだ in before either of these phrases to add a sense of curiosity or speculation to your sentence.

You can add either of these to the casual form of:

a verb (e.g., 行く、行った、行きたい、行かない, etc.)
い i-adjectives
or after nouns or adjectives with a な after

JAPANESE	ROMAJI	ENGLISH
なぜ彼が怒っているのだろう。	Naze kare ga okotte iru no darou.	I wonder why he’s angry.
なんで彼がそんなことを言ったんだろう。	Nande kare ga sonna koto o ittan darou.	Why did he say something like that?

CERTAINTY IN JAPANESE WITH かもしれない

かもしれない kamoshirenai

This beast of a sentence-ender is so useful it can’t be understated.

This translates to something like “maybe” in English and is stuck at the end of sentences without conjugation.

It can be shortened to かも kamo too and has the same meaning.

PATTERN

Sentence + かもしれない

One very important thing to note is that often the direct translation for かもしれない sentences is “maybe x”, but the true meaning might be stronger.

Japanese people don’t often like to give strong opinions, so soften the blow with かもしれない.

For example, “美味しいかも” is directly translated to, “It might be delicious,” but it really means “It’s delicious.”

This is an exercise of “reading the air,” and is something that you’ll get used to over time.

JAPANESE	ROMAJI	ENGLISH
今日は雨が降るかもしれない。	Kyou wa ame ga furu kamoshirenai.	It might rain today.
彼は忙しいかもしれません。	Kare wa isogashii kamoshiremasen.	He might be busy.

View More Examples:

japanese	romaji	english
この本は面白いかもしれない。*	Kono hon wa omoshiroi kamoshirenai.	This book might be interesting.
宴会に行かないかもしれない	Enkai ni ikanai kamoshirenai.	I might not go to the work party.
明日の試験は難しいかもしれない。	Ashita no shiken wa muzukashii kamoshirenai.	Tomorrow’s exam might be difficult.
彼の言い分は正しいかもしれない。	Kare no iibun wa tadashii kamoshirenai.	His argument might be correct.

*NOTE || Very often Japanese people will use this kind of sentence to give their opinion without being forcefully like, “This book is great.”

CERTAINTY IN JAPANESE WITH はずだ

はずだ hazu da

はずだ conveys a strong sense of assurance and can be interpreted as “expected to be” or “ought to.”

This approach signifies that you arrive at conviction through objective analysis.

When linking nouns and な na-adjectives, it’s essential to affix の to nouns and な to な na-adjectives, respectively.

PATTERN

Verbs + はずだ

To make this negative, you can either negate the verb before はずだ or keep the verb the same and add はずがない (which sounds stronger).

JAPANESE	ROMAJI	ENGLISH
彼は試験に合格するはずだ。	Kare wa shiken ni goukaku suru hazu da.	He should pass the exam.
この店の料理は美味しいはずだ。	Kono mise no ryouri wa oishii hazu da.	The food at this restaurant is supposed to be delicious.

View More Examples:

japanese	romaji	english
彼女は今日来るはずだった。	Kanojo wa kyou kuru hazu datta.	She was supposed to come today.
その計画は成功するはずだ。	Sono keikaku wa seikou suru hazu da.	The plan is expected to succeed.
彼はプロなので、上手に演奏するはずだ。	Kare wa puro na node, jouzu ni ensou suru hazu da.	Since he’s a professional, he should play skilfully.

CERTAINTY IN JAPANESE WITH に違いない

に違いない nichigainai

に違いない conveys a strong sense of certainty, just like はずだ.

Yet, it suggests that you arrive at this certainty through your own subjective thinking.

So, に違いない can be used to express gut feelings or instincts.

It doesn’t require any fancy conjugations; you can slap it right onto any part of a sentence.

This sounds a tad formal and is the go-to option in written stuff.

JAPANESE	ROMAJI	ENGLISH
彼が犯人に違いない。	Kare ga hannin ni chigai nai.	He is undoubtedly the culprit.
この結果は正しいに違いない。	Kono kekka wa tadashii ni chigai nai.	There’s no doubt that this result is correct.

View More Examples:

japanese	romaji	english
彼の努力が実を結ぶに違いない。	Kare no doryoku ga mi o musubu ni chigai nai.	His efforts are bound to bear fruit.
彼女の反応から、驚いているに違いない。	Kanojo no hankou kara, odorite iru ni chigai nai.	Judging from her reaction, she must be surprised.
その事件は大きな影響を持つに違いない。	Sono jiken wa ooki na eikyou o motsu ni chigai nai.	That incident is sure to have a significant impact.

CERTAINTY IN JAPANESE WITH 多分

多分 tabun

This is forever confusing for a Japanese learner. It means “probably” or “more than likely” but unfortunately, many Japanese people translate it to, “maybe.”

Whilst “maybe” in English conveys around a 50% chance of something happening, 多分 is more like 80%.

Many Japanese people will use this even when they know something is certainly the case, they just don’t want to be super assertive by saying an outright “yes”.

This is the same as what was mentioned earlier about かもしれない.

A and B are discussing whether they will be going to a party:

^{doyōbi no pātī ni iku no?}

土曜日のパーティーに行くの？

_{Will you go to the party on Saturday?}

^{tabun. Chotto kakunin shite kara messēji suru yo!}

多分。ちょっと確認してからメッセージするよ！

_{Probably (80% certainty). I’ll just quickly check and get back to you}

OTHER WAYS TO EXPRESS CERTAINTY

絶対 zettai

This means “absolutely” and indicates 100% certainty.

For example, if someone asks if you’re going to an event, you could say, 絶対行きますよ zettai ikimasu yo,” to mean, “I’m absolutely going.”

**恐らく*osoraku***

This is what you’d say if you were almost certain something is going to happen.

For example, if you ask your coworker if they’ll be transferred this year and they answer with this, they probably think at about 90% certainty that they’ll be leaving.

This one is often used to indicate bad things in the future.

と思う to omou

An article about expressing certainty wouldn’t be complete without mentioning how to say “I think” in Japanese.

Usually, Japanese people won’t typically use this for strong opinions and such, but more for general things that have little impact on others, such as the weather.

For example, you might here things like this in daily conversation, 明日は雨だと思う ashita ha ame da to omou (I think it will be rainy tomorrow).”

**間違いなく*machigainaku***

This means something along the lines of “definitely,” and as such is used for situations with very high certainty.

This often can be paired with だろう , でしょう orと思う.

SUMMARY

Here’s a quick summary of the lesson about certainty in Japanese:

だろう (informal) and でしょう (formal) both mean “probably” with a fair amount of certainty.
かもしれない and 多分 are like “maybe,” but are often masking more certainty than the direct translation lets on to.
はずだ signifies strong certainty and reflects objective viewpoints.
に違いない denotes high certainty and suggests subjective perspectives while retaining a formal demeanour.
と思う can be used too in conversation.

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FAQs

How to use だろう?

だろう da rou is an informal way to express certainty in Japanese.

The formal way is でしょう de shou (formal).

These two come at the end of a sentence and sound like “probably” or “right?”.

だろうda rou is mostly used by men, so stick to the more polite version, でしょう deshou, if you’re a lady.

You can use either of these with the dictionary form of a verb, or any nouns/adjectives.

Examples:

明日は雨が降るだろうか。

Ashita wa ame ga furu darou ka.

I wonder if it will rain tomorrow.

—

彼はきっと遅れてくるでしょう。

Kare wa kitto okurete kuru deshou.

He will surely come late.

How to use かもしれない?

かもしれない (kamoshirenai) translates to something like “maybe” in English and is stuck at the end of sentences without conjugation.

It can be shortened to かも kamo too and has the same meaning.

One very important thing to note is that often the direct translation for かもしれない kamoshirenai sentences is “maybe x”, but the true meaning might be stronger.

Japanese people don’t often like to give strong opinions, so soften the blow with かもしれない kamoshirenai.

Examples:

今日は雨が降るかもしれない。

Kyou wa ame ga furu kamoshirenai.

It might rain today.

—

彼は忙しいかもしれません。

Kare wa isogashii kamoshiremasen.

He might be busy.

How to use はずだ?

はずだ hazu da conveys a strong sense of assurance and can be interpreted as “expected to be” or “ought to.”

This approach signifies that you arrive at conviction through objective analysis.

When linking nouns and な na-adjectives, it’s essential to affix の no to nouns and な na to な na-adjectives, respectively.

Examples:

この店の料理は美味しいはずだ。

Kono mise no ryouri wa oishii hazu da.

The food at this restaurant is supposed to be delicious.

—

その計画は成功するはずだ。

Sono keikaku wa seikou suru hazu da.

The plan is expected to succeed.

How to express certainty in Japanese?

Here’s a quick summary of the lesson about certainty in Japanese:

– だろう da rou (informal) and でしょう deshou (formal) both mean “probably” with a fair amount of certainty.

– かもしれない kamoshirenai and 多分 tabun are like “maybe,” but are often masking more certainty than the direct translation lets on to.

– はずだ hazu da signifies strong certainty and reflects objective viewpoints.

– に違いない ni chigainai denotes high certainty and suggests subjective perspectives while retaining a formal demeanour.

– と思う to omou can be used too in conversation.

Where can I study more Japanese grammar?

You should have a look at our Japanese Grammar Bank, where we regularly publish free lessons for levels A1, A2 and B1.

Can I learn Japanese with LTL?

Yes, you can!

We teach Japanese online, on our Flexi Classes platform.

We can also organise a language program for you in Tokyo, where you can study in group or individual classes, as well as live with a Japanese family.

Japanese Grammar Bank

CERTAINTY IN JAPANESE

CERTAINTY IN JAPANESE WITH だろう & でしょう

PATTERN #1

PATTERN #2

CERTAINTY IN JAPANESE WITH かもしれない

PATTERN

CERTAINTY IN JAPANESE WITH はずだ

PATTERN

CERTAINTY IN JAPANESE WITH に違いない

CERTAINTY IN JAPANESE WITH 多分