По-твоему, это правильно?

Because this is the standard spelling for adverb-like forms built with по- plus certain pronoun/adjective forms, such as:

• по-моему — in my opinion
• по-твоему — in your opinion
• по-своему — in one’s own way
• по-новому — in a new way

So по-твоему is not written as two separate words here.

Because after по- in this expression, Russian uses a form that historically comes from the dative singular of the pronoun/adjective.

So:

• base form: твой
• form used here: твоему

This is why you also get:

• по-моему
• по-твоему
• по-вашему

A learner does not need to treat this as a freely changeable phrase every time; it is best learned as a fixed expression.

It means something like in your opinion, as far as you’re concerned, or the way you see it.

Grammatically, it functions like an adverbial expression modifying the whole statement, not just one word. It sets the speaker’s frame: according to you.

So in По-твоему, это правильно?, the speaker is asking for the other person’s judgment.

Yes. твой is the informal singular you form, used with friends, family, children, or people you address with ты.

The polite/formal version is:

• По-вашему, это правильно?

That is what you would say to one person you address with вы, or sometimes to a group.

Because по-твоему is being used as a parenthetical or introductory expression, similar to in your opinion in English.

So Russian normally separates it with a comma:

• По-твоему, это правильно?

This comma shows that the phrase comments on the whole sentence rather than acting as a regular sentence part inside it.

Yes. Russian word order is flexible.

You can say:

• По-твоему, это правильно?
• Это, по-твоему, правильно?

Both are natural, but the emphasis changes a little:

• По-твоему, это правильно? = starts with in your opinion
• Это, по-твоему, правильно? = puts more focus on this

The second version can sound a bit more pointed or skeptical in some contexts.

They are close, but not always identical.

• правильно often means correct, right, proper, or the right way
• верно often means true, accurate, or correct

In many situations both work, but правильно can sound broader: not only factually correct, but also proper or appropriate.

So По-твоему, это правильно? may ask not just Is it factually correct? but also Do you think this is the right/proper thing?

The stress is on the first syllable of твоему:

• по-твОему

A rough pronunciation guide is:

• pa-TVÓ-ye-mu

The е after the stressed о often sounds like ye.

Yes. In some contexts, по-твоему can also mean your way or the way you do it.

For example:

• Сделай по-твоему. — Do it your way.

So context matters. In По-твоему, это правильно?, it clearly means in your opinion, not your way.

It can be neutral, but intonation matters a lot.

• With a calm tone, it is a normal request for someone’s opinion.
• With a sharper tone, it can sound doubtful, challenging, or even annoyed: You really think this is right?

That is very common in Russian: the same words can sound neutral or confrontational depending on intonation and context.