postajati / postati (to become) | Croatian Grammar

Postati ("to become") is the verb of change of state, and its one essential lesson is the instrumental of result: when you become something, that something can go in the instrumental — postati liječnikom ("become a doctor"). Alternatively the predicate appears in the nominative, which is more common in casual speech: postati liječnik. Adjectives, by contrast, normally stay in the nominative: postati poznat ("become famous"). This page gives you the full paradigm and a clear rule for choosing the predicate case.

Aspect

This is a clean aspectual pair:

postati (pf) — the moment of becoming, a completed transition: Postao je slavan preko noći ("He became famous overnight").
postajati (impf) — becoming gradually, a process underway: Postaje sve hladnije ("It's getting colder and colder").

Reach for the perfective when the change is achieved and the imperfective when it is unfolding. Note that the two have different present stems: perfective postanem, imperfective postajem. Aspect basics are at aspect overview.

💡

Croatian distinguishes biti ("be" — a state) from postati ("become" — a transition into that state). On je liječnik = "he is a doctor"; On je postao liječnik(om) = "he became a doctor". Don't reach for biti when you mean the change itself.

Present tense

The perfective postati has the present stem postan- (postanem); the imperfective postajati has postaj- (postajem). Both follow the same set of endings.

Person	postati (pf)	postajati (impf)
ja	postanem	postajem
ti	postaneš	postaješ
on/ona/ono	postane	postaje
mi	postanemo	postajemo
vi	postanete	postajete
oni/one/ona	postanu	postaju

As a perfective, postanem does not describe a "becoming" happening right now — it appears in subordinate and future-leaning clauses. For the live, gradual sense, use the imperfective postaje.

Svake jeseni dani postaju kraći.

Every autumn the days become shorter. — imperfective 'postaju', gradual process.

Kad postaneš punoljetan, sve se mijenja.

When you become an adult, everything changes. — perfective 'postaneš' in a 'when' clause.

The l-participle

Built on the infinitive stem posta-: masculine postao, feminine postala, neuter postalo. The masculine postao shows the vocalised -l.

Gender / number	Form
masculine singular	postao
feminine singular	postala
neuter singular	postalo
masculine plural	postali
feminine plural	postale
neuter plural	postala

Perfect tense (perfekt)

Clitic biti + l-participle. This is the everyday way to report a completed change.

Person	Masculine subject	Feminine subject
ja	postao sam	postala sam
ti	postao si	postala si
on / ona	postao je	postala je
mi	postali smo	postale smo
vi	postali ste	postale ste
oni / one	postali su	postale su

Postala je najmlađa direktorica u tvrtki.

She became the youngest director in the company. — feminine speaker, nominative predicate.

S vremenom su postali dobri prijatelji.

Over time they became good friends. — nominative plural predicate.

Future I (futur prvi)

The infinitive postati drops its final -i before the clitic: postat ću.

Person	Form
ja	postat ću
ti	postat ćeš
on/ona/ono	postat će
mi	postat ćemo
vi	postat ćete
oni/one/ona	postat će

Jednog dana postat ćeš odličan učitelj.

One day you'll become an excellent teacher. — nominative predicate 'odličan učitelj'.

Imperative

The perfective gives postani, postanimo, postanite. It is used motivationally — "become …!".

Person	Form
ti	postani
mi	postanimo
vi	postanite

Postani najbolja verzija sebe.

Become the best version of yourself.

Conditional I (kondicional prvi)

bih-clitics + l-participle.

Person	Form (masc.)
ja	postao bih
ti	postao bi
on/ona/ono	postao/postala/postalo bi
mi	postali bismo
vi	postali biste
oni/one/ona	postali bi

Da imam više vremena, postao bih bolji kuhar.

If I had more time, I'd become a better cook.

Other forms

Passive participle: none — postati is intransitive (it links a subject to a predicate; it does not take a direct object), so it has no passive.
Present verbal adverb: postajući ("becoming") is built from the imperfective and turns up in writing: Postajući sve poznatiji, gubio je privatnost ("Becoming ever more famous, he was losing his privacy").

Tehnologija, postajući sve jeftinija, mijenja svakodnevicu.

Technology, becoming ever cheaper, is changing daily life. — verbal adverb 'postajući'.

Key uses and government — the predicate case

1. postati + instrumental — the "instrumental of result"

A noun predicate that names what someone becomes goes most properly in the instrumental: postati liječnikom, učiteljicom, predsjednikom. This is the same instrumental that marks a temporary or resultant role, treated at predicate instrumental. It reads as slightly more formal or careful.

Nakon godina truda postao je liječnikom.

After years of effort he became a doctor. — instrumental 'liječnikom'.

Želi postati odvjetnicom kao njezina majka.

She wants to become a lawyer like her mother. — instrumental 'odvjetnicom'.

2. postati + nominative — the colloquial alternative

The same noun predicate may stand in the nominative, and this is what you hear most in everyday speech: postati liječnik. Both are correct; choose the instrumental for formal register, the nominative for casual.

Postao je tata prošle godine.

He became a dad last year. — nominative predicate 'tata', colloquial.

3. postati + adjective — nominative, agreeing

When what you become is an adjective, it stays in the nominative and agrees with the subject in gender and number, following normal predicate agreement.

Preko noći je postala slavna.

She became famous overnight. — nominative feminine adjective 'slavna'.

Postali su nervozni kad je kasnila.

They got nervous when she was running late. — nominative plural adjective 'nervozni'.

Common Mistakes

❌ On je postao liječnika.

Case error — the result noun is instrumental ('liječnikom') or nominative ('liječnik'), never accusative/genitive.

✅ On je postao liječnik. / On je postao liječnikom.

He became a doctor. — nominative (casual) or instrumental (formal).

❌ Postala je slavnom.

An adjective predicate stays in the nominative: 'postala je slavna' (the instrumental is for nouns).

✅ Postala je slavna.

She became famous.

❌ On je liječnik prošle godine.

Wrong verb — 'biti' states a fact; for the change use 'postati': 'Postao je liječnik prošle godine'.

✅ Postao je liječnik prošle godine.

He became a doctor last year.

❌ Dani postaju kraći postanu.

Aspect confusion — for the gradual ongoing process use the imperfective present 'postaju', not the perfective 'postanu'.

✅ Dani postaju sve kraći.

The days are getting shorter and shorter.

❌ Postaću učitelj.

Spelling — the future drops the infinitive -i and is written separately: 'postat ću učitelj'.

✅ Postat ću učitelj.

I'll become a teacher.

Key Takeaways

postati (pf, postanem) / postajati (impf, postajem) — note the two different present stems.
A noun predicate goes in the instrumental (formal: postati liječnikom) or the nominative (casual: postati liječnik) — both correct.
An adjective predicate stays in the nominative and agrees: postati slavna / nervozni.
Use postati for the change into a state; biti for the state itself.
Future postat ću; imperative postani; verbal adverb postajući.

Now practice Croatian

Reading grammar gets you part of the way. The exercises are where it sticks — free, no signup needed.

Start learning Croatian→