być and mieć Side by Side | Polish Grammar

The first two verbs you will reach for in Polish are być ("to be") and mieć ("to have"), and they are also the two that English speakers confuse most — not because the forms are hard, but because Polish splits up jobs that English hands to a single word. This page puts the two paradigms next to each other and, more importantly, shows you what each verb attaches to, because that is where the real difficulty lives.

The two paradigms, side by side

Both verbs are irregular, but each is irregular in its own contained way — you simply memorize the six forms and you are done. Notice that być is suppletive: the singular and jesteśmy/jesteście run off a jest- base (jestem, jesteś, jest, jesteśmy, jesteście), but the third plural są is a different root entirely. mieć, by contrast, has a clean, predictable stem ma- throughout.

Person	być (to be)	mieć (to have)
ja (I)	jestem	mam
ty (you, sg.)	jesteś	masz
on / ona / ono (he/she/it)	jest	ma
my (we)	jesteśmy	mamy
wy (you, pl.)	jesteście	macie
oni / one (they)	są	mają

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Memorize these twelve forms as a block before anything else. They appear in almost every sentence you will say in your first month, and getting jest ("is") and są ("are") automatic will save you constant hesitation.

A reassuring point for English speakers: Polish has no continuous tense. "Jestem" covers both "I am" and (where English would say) "I am being," and there is no separate progressive. You also normally drop the pronoun, because the verb ending already tells you the person — jestem can only mean "I am." You add ja, ty etc. only for contrast or emphasis.

Jestem głodny, a ty?

I'm hungry, and you?

Mamy dwoje dzieci.

We have two children.

Oni są z Krakowa, a my jesteśmy z Gdańska.

They're from Kraków, and we're from Gdańsk.

być: identity, location, existence

być answers "who/what/where/how is something." Its core jobs:

Identity — saying what someone is: a teacher, a student, a Pole.
Location and existence — saying where something is, or that it exists at all.
Description — pairing with an adjective: tired, happy, big.

Here is the single most important rule on this page, and the one English never prepares you for: być takes the instrumental case for a noun, but the nominative for an adjective.

When you say what someone is — a noun naming a category — that noun goes into the instrumental:

Jestem nauczycielem.

I'm a teacher. (nauczyciel → instrumental nauczycielem)

Ona jest lekarką.

She's a doctor. (lekarka → instrumental lekarką)

Oni są studentami.

They're students. (studenci → instrumental studentami)

But when you describe someone with an adjective, the adjective stays in the nominative and simply agrees in gender:

Jestem zmęczony.

I'm tired. (man speaking — nominative masculine)

Jestem zmęczona.

I'm tired. (woman speaking — nominative feminine)

Ta zupa jest bardzo dobra.

This soup is very good. (adjective, nominative)

Why the split? Because the instrumental here marks a role or category you slot into — a hat you wear, something you can take off and put on (you can stop being a teacher). An adjective, by contrast, just describes a quality of the subject directly, so it agrees with it like any other adjective. Once you feel that "instrumental = a label/role, nominative = a quality," the choice stops being arbitrary. See the predicate instrumental page for the full story.

For existence and location, być behaves like plain English "to be," with no case surprises beyond whatever the preposition demands:

Mama jest w kuchni.

Mum is in the kitchen.

Czy jest tu wolne miejsce?

Is there a free seat here?

mieć: possession, age, and "have to"

mieć answers "what does someone have." Its direct object goes in the accusative — the case for the thing being possessed or acted on:

Mam nowy telefon.

I have a new phone. (telefon, accusative = nominative for this inanimate noun)

Masz ładny dom.

You have a nice house.

Czy masz długopis?

Do you have a pen?

Crucially, under negation the object of mieć switches to the genitive — this is the genitive of negation, and it is obligatory:

Nie mam czasu.

I don't have time. (czas → genitive czasu)

Ona nie ma samochodu.

She doesn't have a car. (samochód → genitive samochodu)

The trap: English "be"-states that are mieć in Polish

This is where English speakers leak the most errors. A whole cluster of states that English builds with "to be" are built in Polish with mieć, because Polish treats them as things you possess, not states you are in. The headline case is age:

Mam dwadzieścia lat.

I'm twenty (years old). — literally 'I have twenty years'

Ile masz lat?

How old are you? — literally 'How many years do you have?'

Mój syn ma pięć lat.

My son is five years old.

Other high-frequency "have"-states where English uses "be":

Masz rację.

You're right. — literally 'you have rightness'

Mam ochotę na kawę.

I feel like a coffee. — literally 'I have a desire for coffee'

And note mieć + infinitive, which is one way Polish expresses a soft obligation or arrangement ("be supposed to / be to"):

Mam dzisiaj zadzwonić do lekarza.

I'm supposed to call the doctor today.

Quick decision guide

When you reach for "is/am/are/have," ask one question first: am I naming, locating, or describing — or am I possessing?

You want to say…	Use	Completion	Example
X is a [noun/role]	być	instrumental	Jestem inżynierem.
X is [adjective]	być	nominative	Jestem szczęśliwy.
X is [location] / exists	być	(preposition's case)	Jest w domu.
X has [a thing]	mieć	accusative	Mam psa.
X doesn't have [a thing]	mieć + nie	genitive	Nie mam psa.
X is [N] years old	mieć	accusative (years)	Mam trzydzieści lat.

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If you can rephrase the English with "to possess," it is almost always mieć: "I possess twenty years," "I possess time," "I possess a desire." This rough test catches the age/rightness/desire cluster that trips up beginners.

Common Mistakes

❌ Jestem dwadzieścia lat.

Incorrect — age uses mieć, not być.

✅ Mam dwadzieścia lat.

I'm twenty years old.

❌ Jestem nauczyciel.

Incorrect — a predicate noun after być must be instrumental, not nominative.

✅ Jestem nauczycielem.

I'm a teacher.

❌ Jestem zmęczonym.

Incorrect — an adjective after być stays nominative; don't put it in the instrumental.

✅ Jestem zmęczony.

I'm tired.

❌ Nie mam czas.

Incorrect — the object of a negated verb must be genitive.

✅ Nie mam czasu.

I don't have time.

❌ Masz rację? Tak, ja jestem rację.

Incorrect — 'be right' is mieć rację, never być.

✅ Masz rację? Tak, mam rację.

Are you right? Yes, I'm right.

Key Takeaways

być = jestem, jesteś, jest, jesteśmy, jesteście, są.
mieć = mam, masz, ma, mamy, macie, mają.
After być: instrumental for a noun role, nominative for an adjective.
After mieć: accusative for the object, but genitive under negation.
Many English "be"-states (age, being right, feeling like) are mieć in Polish.

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