Мой телефон дороже, чем книга.

My phone is more expensive than a book.

Breakdown of Мой телефон дороже, чем книга.

• мой: my
• книга: the book
• телефон: the phone
• чем: than
• дороже: more expensive

Questions & Answers about Мой телефон дороже, чем книга.

Why is дороже used here instead of более дорогой?

Russian has two ways to form comparatives of adjectives:

• Synthetic comparatives (one-word forms): дороже, моложе, старше, быстрее
• Analytic comparatives (two-word forms with более/менее): более дорогой, менее дорогой

For most common adjectives—especially those with one or two syllables—the synthetic form (дороже) is more idiomatic and concise. The analytic form (более дорогой) exists and is perfectly correct, but it sounds heavier in everyday speech.

How is дороже formed from the adjective дорогой?

Morphologically, дорогой → дороже is formed by:

1. Dropping the ending -ой
2. Softening the stem consonant г → ж (a regular phonetic change)
3. Adding the comparative ending -е

So дорог- + ж + е = дороже.

Why is there a comma before чем?

In Russian, when you introduce a comparison with the conjunction чем (“than”), you treat the second part as a subordinate clause. Standard punctuation rules require a comma before чем to mark the boundary:

Мой телефон дороже, чем книга.
↑ comma here

Omitting this comma in writing is considered non-standard, though in rapid speech it may not be pronounced distinctly.

What case does книга take after чем?

After the conjunction чем the noun stays in the nominative case. Чем here is a conjunction, not a preposition, so it does not affect the case of the noun:

…, чем книга (NOM)

Can we drop чем and use a different case for “the book”?

Yes. Many comparatives in colloquial and even in written Russian can directly govern the genitive without чем:

Мой телефон дороже книги.

Here книги is in the genitive case. This construction is very common in speech and informal writing. In formal or carefully edited text, however, the pattern with чем + nominative is often preferred.

What part of speech is чем in this sentence? Is it a preposition?

In дороже, чем книга the word чем is a conjunction introducing a comparative clause (“than”). It is not the preposition чем you see in fixed expressions (e.g. чем-либо). Because it’s a conjunction, it doesn’t require the noun after it to change case.

Why is мой телефон in the nominative case?

Мой телефон is the subject of the sentence. Russian omits the verb “to be” in the present tense, but the subject still appears in the nominative:

[Мой телефон]ₙₒₘ дороже, чем книга.

How would you express a stronger comparison, like “My phone is much more expensive than the book”?

You can insert an intensifier between the subject and дороже, or before дороже:

• Мой телефон намного дороже, чем книга.
• Мой телефон гораздо дороже, чем книга.
• Мой телефон намного более дорогой, чем книга. (analytical comparative)
• Мой телефон значительно дороже книги. (using genitive, no чем)