być — to be | Polish Grammar

być ("to be") is the hub of the entire Polish verb system — and its most irregular verb. Its present tense is built from a different root than the rest of its paradigm, its future tense (będę...) powers the whole imperfective future of every other Polish verb, and it is the verb you need before you can say almost anything. This page is the complete reference: every paradigm in a table, plus the three predicate patterns that unlock basic Polish — instrumental for noun predicates, nominative for adjectives, and nie ma + genitive for negated existence.

być is imperfective only: it has no perfective partner. When you need the perfective idea of "to be(come)", Polish switches to a different verb — zostać or stać się ("to become"). So być carries no aspect choice; there is exactly one verb of "being".

Present tense

The present is suppletive (built on the root jest- / są), and it is the irregular paradigm every learner memorizes first.

Person	Form	Meaning
ja	jestem	I am
ty	jesteś	you are (sg.)
on / ona / ono	jest	he / she / it is
my	jesteśmy	we are
wy	jesteście	you are (pl.)
oni / one	są	they are

Jestem z Polski, a ty skąd jesteś?

I'm from Poland — and where are you from?

Oni są już w domu.

They're already home.

Past tense (by gender)

Like all Polish past tenses, być's past agrees in gender. The stem is był-, and the gendered endings attach to it. Note the masculine-personal vs. non-masculine-personal split in the plural — byli for groups that include at least one man, były otherwise.

Person	Masculine	Feminine	Neuter
ja	byłem	byłam	—
ty	byłeś	byłaś	—
on / ona / ono	był	była	było
my	byliśmy	byłyśmy	—
wy	byliście	byłyście	—
oni / one	byli (masc. pers.)	były (all others)

Wczoraj byłam u lekarza.

Yesterday I was at the doctor's. (a woman speaking)

Byliśmy razem na studiach.

We were at university together. (a group including men)

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The personal endings (-em, -eś, -śmy, -ście) are "floating" — they can detach from the verb and hop onto an earlier stressed word in the clause: gdzie byłeś? but also gdzieś był? ("where were you?"). With być this is everyday and colloquial; you'll hear czemuś taki smutny? ("why are you so sad?") with the -ś of jesteś/byłeś clitically attached to czemu.

Future tense

The future is built on the root będ-. This paradigm is doubly important: it is być's own future, and it serves as the auxiliary for the compound imperfective future of every other verb (będę czytać / będę czytał = "I will read").

Person	Form	Meaning
ja	będę	I will be
ty	będziesz	you will be (sg.)
on / ona / ono	będzie	he / she / it will be
my	będziemy	we will be
wy	będziecie	you will be (pl.)
oni / one	będą	they will be

Będę w biurze do piątej.

I'll be in the office until five.

Czy będziecie jutro w domu?

Will you be home tomorrow?

Imperative

The imperative stem is bądź- (note the ą and the soft dź). There is no 1st-person singular imperative, as in all Polish verbs.

Person	Form	Meaning
ty	bądź	be! (to one person)
my	bądźmy	let's be
wy	bądźcie	be! (to several)
on/ona (3rd person)	niech będzie	let him/her/it be

Bądź ostrożny na drodze!

Be careful on the road!

Niech będzie, jak chcesz.

Let it be the way you want. (= fine, have it your way)

Conditional

The conditional adds the -by particle plus past-like personal endings to the był- stem — and it, too, agrees in gender.

Person	Masculine	Feminine
ja	byłbym	byłabym
ty	byłbyś	byłabyś
on / ona	byłby	byłaby
my	bylibyśmy	byłybyśmy
wy	bylibyście	byłybyście
oni / one	byliby	byłyby

Byłbym wdzięczny za szybką odpowiedź.

I would be grateful for a quick reply. (a man writing, formal)

Verbal adverb and other non-finite forms

Form	być	Meaning
Infinitive	być	to be
Contemporary verbal adverb	będąc	being

The verbal adverb będąc is mildly irregular — built on the future stem będ-, not the present są. It behaves like any contemporary verbal adverb in -ąc: indeclinable, simultaneous, same subject.

Będąc w Warszawie, koniecznie zobacz Stare Miasto.

When you're in Warsaw, be sure to see the Old Town.

być has no active adjectival participle (*będący is not standard) and no passive participle of its own — fitting for a verb that has no perfective partner.

Usage: the three completions of być

What follows być is governed by a precise pattern. Internalize these three cases and basic Polish opens up.

1. Noun predicate → instrumental

When być links the subject to a noun ("X is a Y"), that noun goes in the instrumental, not the nominative. This is the single most distinctive feature of Polish być for English speakers.

Mój brat jest inżynierem.

My brother is an engineer. (inżynier → instrumental inżynierem)

Chcę zostać lekarzem.

I want to become a doctor. (zostać also takes the instrumental)

See the dedicated page on the instrumental predicate for the full treatment.

2. Adjective predicate → nominative

When być links the subject to an adjective ("X is [adjective]"), the adjective stays in the nominative and agrees in gender and number. This is the contrast learners must hold against the noun rule.

Jestem bardzo zmęczony.

I'm very tired. (a man; zmęczony, nominative)

Te jabłka są naprawdę słodkie.

These apples are really sweet. (słodkie, nominative plural)

So: jestem nauczycielem (noun, instrumental) but jestem dobry (adjective, nominative). Keeping these two apart is the heart of mastering być.

3. Existence → jest / są, but negated existence → nie ma + genitive

To state that something exists or is present, być uses jest (singular) / są (plural) with the nominative subject. But the negative is wildly irregular: "there isn't / there aren't" is nie ma + genitive — not nie jest. nie ma literally uses the verb mieć ("to have"), frozen impersonally, and is the same in all three tenses for negated existence (nie ma → nie było → nie będzie).

Czy jest tu wolne miejsce? — Nie, nie ma.

Is there a free seat here? — No, there isn't.

W lodówce nie ma mleka.

There's no milk in the fridge. (mleko → genitive mleka)

Wczoraj nie było cię na zajęciach.

You weren't at class yesterday. (negated existence, past: nie było + gen.)

The full treatment is on the nie ma + genitive page.

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The mental switch for być predicates: noun → instrumental, adjective → nominative, "there isn't" → nie ma + genitive. These three patterns cover the overwhelming majority of być sentences, and getting them automatic is what separates beginner from functional Polish.

być as auxiliary

być is a workhorse auxiliary in two constructions:

Compound imperfective future: będę
- infinitive (or + past-like -ł form). Będę pracować / będę pracował = "I will work / be working".
Passive voice: być
- passive participle gives a stative/imperfective passive. Dom jest budowany = "the house is being built"; contrast the dynamic zostać passive (dom został zbudowany = "the house was built"). See passive with być vs zostać.

Jutro będę cały dzień czytał do egzaminu.

Tomorrow I'll be studying for the exam all day. (compound future)

Sklep jest otwarty od ósmej.

The shop is open from eight. (być + participle, stative)

Common Mistakes

1. Nominative noun predicate instead of instrumental. "I am a teacher" needs the instrumental.

❌ Jestem nauczyciel.

Incorrect — a noun predicate after być takes the instrumental.

✅ Jestem nauczycielem.

I am a teacher.

2. Putting an adjective predicate in the instrumental. Adjectives after być stay nominative.

❌ Jestem zmęczonym.

Incorrect — an adjective predicate stays in the nominative.

✅ Jestem zmęczony.

I'm tired.

3. Using nie jest for "there isn't". Negated existence is nie ma + genitive.

❌ Nie jest chleba w domu.

Incorrect — for 'there's no bread' use nie ma + genitive.

✅ Nie ma chleba w domu.

There's no bread at home.

4. Missing diacritics in the future/imperative stems. It is będę / bądź, never bede / badz.

❌ Bede gotowy za chwile.

Incorrect — the nasal vowels are required: będę, chwilę.

✅ Będę gotowy za chwilę.

I'll be ready in a moment.

Key Takeaways

być is the most irregular and most essential verb: suppletive present (jestem...są), był- past (gendered), będ- future, bądź imperative, byłbym conditional, będąc adverb.
It is imperfective-only — for the perfective "become", use zostać / stać się.
Its będę future is the auxiliary for the whole imperfective future of other verbs.
Three predicate completions: noun → instrumental, adjective → nominative, negated existence → nie ma + genitive.

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