По-моему, он прав.

По-моему means in my opinion, as for me, or to my mind.

So:

• По-моему, он прав. = In my opinion, he is right.

It is very common in Russian and often sounds a bit more natural and idiomatic than always saying я думаю.

Compare:

• Я думаю, он прав. = I think he is right.
• По-моему, он прав. = In my opinion, he is right.

The difference is small, but по-моему sounds a little more like you are giving your personal view, while я думаю focuses more on the act of thinking.

Because по-моему is a fixed adverbial expression, and Russian writes forms like this with a hyphen.

This pattern is common with expressions such as:

• по-моему = in my opinion
• по-твоему = in your opinion
• по-нашему = in our opinion / in our way
• по-русски = in Russian

So the hyphen is just part of the standard spelling here. You should learn по-моему as one set expression.

Моему is the dative singular form of мой.

The phrase по-моему comes from an old pattern with по + dative, roughly meaning something like according to my... or by my way of seeing it.

You do not need to reconstruct it every time; for learners, it is best to memorize по-моему as a chunk meaning in my opinion.

Related forms:

• по-твоему = in your opinion
• по-вашему = in your opinion
• по-нашему = in our opinion

Because по-моему is being used as a parenthetical expression, like in my opinion in English.

So Russian normally writes:

• По-моему, он прав.

That comma shows that по-моему is not part of the main grammatical structure of он прав. It is a comment from the speaker.

You may also see it in the middle of a sentence, where it is usually set off with commas:

• Он, по-моему, прав. = He, in my opinion, is right.

In Russian, the verb to be is usually omitted in the present tense.

So:

• Он прав. literally looks like He right.
• But it means He is right.

This is completely normal in Russian.

Compare:

• Он студент. = He is a student.
• Она дома. = She is at home.
• Они готовы. = They are ready.

In the past or future, Russian does use forms of быть:

• Он был прав. = He was right.
• Он будет прав. = He will be right.

Because прав here is the short form of the adjective правый/прав in the sense of right, correct.

In this sentence, прав means correct or in the right.

• Он прав. = He is right.

This is a very common short-form adjective used predicatively, especially after a subject.

By contrast, правый usually means right-hand/right-side or sometimes right-wing depending on context:

• правая рука = right hand
• правый берег = right bank
• правый политик = right-wing politician

So in он прав, you need прав, not правый.

Yes. It agrees with the person or thing that is being described.

Forms:

• он прав = he is right
• она права = she is right
• оно право = it is right
• они правы = they are right

Examples:

• Ты прав. = You are right. (to a man / boy, or informal masculine)
• Ты права. = You are right. (to a woman / girl)
• Вы правы. = You are right. (formal singular or plural)

This is very important, because Russian adjectives usually agree in gender and number.

Yes. Russian word order is flexible, and changing it can slightly change the emphasis.

The most neutral version is:

• По-моему, он прав.

You could also say:

• Он, по-моему, прав.
• Он прав, по-моему.

These all mean roughly the same thing, but the focus shifts a little:

• По-моему, он прав. = starts with your opinion
• Он, по-моему, прав. = focuses first on he
• Он прав, по-моему. = adds in my opinion at the end, almost as an afterthought

For a learner, the first version is the safest and most standard.

A practical pronunciation guide is:

• па-МО-yi-mu, on PRAF

A few notes:

• The stress in по-моему is on the first syllable of моему: по-МОему
• The stress in прав is on the only syllable: прав
• Final в in прав is pronounced like f at the end of the word, so it sounds roughly like praf

A more careful approximation:

• [pa-MO-ye-mu, on praf]

Yes, very often.

Common forms:

• по-моему = in my opinion
• по-твоему = in your opinion (informal singular)
• по-вашему = in your opinion (formal singular or plural)
• по-нашему = in our opinion
• по-ихнему exists in colloquial speech, but it is nonstandard; standard Russian usually prefers по их мнению instead

Examples:

• По-твоему, это нормально? = Do you think this is normal? / In your opinion, is this normal?
• По-вашему, что нужно делать? = What do you think should be done?

Yes, very natural.

It is a short, common, conversational way to say that you think someone is correct. Native speakers use this kind of sentence all the time.

Depending on tone and context, it can sound:

• neutral
• thoughtful
• mildly argumentative
• supportive

For example:

• По-моему, он прав. = I think he’s right.
• Нет, по-моему, он не прав. = No, I think he’s wrong.

So this is definitely a sentence worth learning as a whole.