Moje sestra je mladší než já.

My sister is younger than I am.

Breakdown of Moje sestra je mladší než já.

• já: I
• být: to be
• můj: my
• než: than
• sestra: the sister
• mladší: younger

Questions & Answers about Moje sestra je mladší než já.

What does each word in Moje sestra je mladší než já correspond to in English?

Roughly, word by word:

• Moje – my
• sestra – sister
• je – is
• mladší – younger
• než – than
• já – I / me (here: than I (am))

So the whole sentence means: My sister is younger than I am / My sister is younger than me.

Why is it moje sestra and not můj sestra?

Because sestra (sister) is grammatically feminine, and the possessive můj / moje must agree in gender with the noun it modifies.

• Masculine: můj bratr – my brother
• Feminine: moje sestra – my sister
• Neuter: moje dítě – my child

So:

• můj sestra – incorrect (wrong gender)
• moje sestra – correct

What is the difference between moje sestra and má sestra?

Both can mean my sister in the nominative case and are grammatically correct:

• moje sestra – neutral, very common in everyday speech
• má sestra – more formal, stylistically a bit literary or bookish in modern Czech

In conversation, learners are safest using moje sestra. You will see má sestra more in writing, literature, and sometimes in more elevated style.

Why is it sestra and not some other form like sestru or sestře?

Sestra is in the nominative singular because it is the subject of the sentence:

• Kdo je mladší? – Moje sestra.
  (Who is younger? – My sister.)

Czech nouns change their endings depending on their grammatical role (case). Some key forms of sestra:

• Nominative (subject): sestra – My sister is younger. (Moje sestra je mladší.)
• Accusative (object): sestru – I see my sister. (Vidím svoji sestru.)
• Dative (to/for): sestře – I am writing to my sister. (Píšu sestře.)

Here we are simply saying who is younger, so nominative sestra is used.

Why do we need je? Could we just say Moje sestra mladší než já?

No, you must include je here. In standard Czech, the verb být (to be) is used in the present tense in normal statements:

• Moje sestra je mladší než já. – My sister is younger than I (am).

Leaving out je in this kind of neutral sentence would be incorrect. Unlike some Slavic languages that sometimes drop the present-tense to be, Czech normally keeps it in standard speech and writing.

What is the base form of mladší, and how is this comparative formed?

The base (positive) form is:

• mladý – young

The comparative (younger) is:

• mladší – younger

This is a regular pattern for many one-syllable adjectives:

• mladý → mladší (young → younger)
• starý → starší (old → older)
• krátký → kratší (short → shorter)

You do not normally say více mladý for younger; you use the synthetic comparative form mladší.

Why does mladší look the same for sister (feminine) and I (masculine)? Shouldn’t it change?

Many Czech adjectives form their comparative in -ší / -ější, and in the nominative singular the comparative form is the same for masculine, feminine, and neuter:

• Masculine: Můj bratr je mladší. – My brother is younger.
• Feminine: Moje sestra je mladší. – My sister is younger.
• Neuter: Moje dítě je mladší. – My child is younger.

So you don’t see gender differences in the nominative singular of mladší; the agreement is there in the grammar, but not visible in the form.

Why is it než já and not než mě / mne, like English than me?

In standard Czech, when you compare two subjects, the pronoun after než is normally in the nominative (the “dictionary form”):

• Moje sestra je mladší než já.
  My sister is younger than I (am).

The logic is that there is an implied verb:

• Moje sestra je mladší než já (jsem).
  My sister is younger than I (am).

Since já would be the subject of jsem, it stays in the nominative.

In colloquial speech, some people do say než mě, by analogy with English than me, but this is considered non‑standard or less correct in careful written Czech. For learners, než já is the safe, correct choice.

Can I say Moje sestra je mladší než já jsem or než jsem já? Is that more correct?

All of these are grammatically possible, but differ in style and emphasis:

1. Moje sestra je mladší než já.
   – Standard, natural, the most common form.

2. Moje sestra je mladší než já jsem.
   – Grammatically okay, sounds a bit heavy / emphatic; usually unnecessary in everyday speech.

3. Moje sestra je mladší než jsem já.
   – Also possible, with stronger emphasis on já (than I am).

In normal conversation and writing, Moje sestra je mladší než já is the best and most neutral version.

Can I drop moje and just say Sestra je mladší než já?

Yes, if the context makes it clear whose sister you mean.

• If you are already talking about your family, Sestra je mladší než já will be understood as My sister is younger than I am.
• If there is any risk of confusion (someone else’s sister, another sibling, etc.), use moje sestra.

So:

• Moje sestra je mladší než já. – clear on its own.
• Sestra je mladší než já. – natural in context, slightly less explicit out of context.

Is než the only word for than in comparisons? What about nežli?

In modern Czech:

• než is the normal, everyday word for than in comparisons:

  • Moje sestra je mladší než já.

• nežli is an older, more literary or poetic variant:

  • Moje sestra je mladší nežli já. – sounds elevated / old‑fashioned.

For normal speech and writing, learners should use než.

Are there other common word orders for this sentence, and do they change the meaning?

The basic, neutral order is:

• Moje sestra je mladší než já.

Other variants:

• Sestra je mladší než já. – still neutral, just without moje.
• Moje sestra je než já mladší. – incorrect; než must come right before what you are comparing with (já).
• Mladší než já je moje sestra. – possible but marked; sounds like you are emphasizing younger than I am is my sister (e.g., in contrast to someone else).

For normal use, stick to:

• Moje sestra je mladší než já.