Poniedziałek jest pierwszym dniem tygodnia.

Breakdown of Poniedziałek jest pierwszym dniem tygodnia.

być
to be
dzień
the day
pierwszy
first
tydzień
the week
poniedziałek
Monday

Questions & Answers about Poniedziałek jest pierwszym dniem tygodnia.

Why is Poniedziałek capitalized?
In Polish, days of the week are normally written with a lowercase letter (e.g. poniedziałek) unless they start a sentence or appear in a title. Here Poniedziałek is the first word, so it’s capitalized by the general rule of sentence-initial capitalization.
Why is dniem in the instrumental case?

After the verb jest (to be), when you state what something is (role, attribute, classification), Polish uses the instrumental case for the predicate noun.
Example:
On jest lekarzem. (He is a doctor.)
Poniedziałek jest pierwszym dniem tygodnia.

Why is pierwszym in that form?
Pierwszym is the ordinal numeral pierwszy (first) declined into the masculine singular instrumental form (pierwszypierwszym) so that it agrees in gender, number, and case with dniem (also masculine singular instrumental).
Why is tygodnia in the genitive case?

The phrase “day of the week” is a partitive or “of-” construction. In Polish the second noun in such phrases takes the genitive case:
dzień tygodnia = “a day of the week.”
Here tydzień becomes tygodnia (genitive singular).

Can I use to instead of jest?

Yes. A very common alternative is:
Poniedziałek to pierwszy dzień tygodnia.
When you use to as the linking word, both parts remain in the nominative case (poniedziałek, pierwszy dzień tygodnia).

How would I say “the first day of the week” by itself in Polish?
As a standalone noun phrase (nominative), you say pierwszy dzień tygodnia. It only turns into pierwszym dniem tygodnia in your sentence because of the instrumental requirement after jest.
How do I ask “What day of the week is Monday?” in Polish?

Two natural ways are:
1) Using jest and instrumental:
Którym dniem tygodnia jest poniedziałek?
2) Using to and nominative:
Poniedziałek to który dzień tygodnia?

Can I invert the sentence for emphasis?

Yes. Depending on which element you front, the cases remain the same:
Pierwszym dniem tygodnia jest poniedziałek. (instrumental)
Pierwszy dzień tygodnia to poniedziałek. (nominative with to)

AI Language TutorTry it ↗
What's the best way to learn Polish grammar?
Polish grammar becomes intuitive with practice. Focus on understanding the core patterns first — how sentences are structured, how verbs change form, and how words relate to each other. Our course breaks these concepts into small lessons so you can build understanding step by step.

Sign up free — start using our AI language tutor

Start learning Polish

Master Polish — from Poniedziałek jest pierwszym dniem tygodnia to fluency

All course content and exercises are completely free — no paywalls, no trial periods.

  • Infinitely deep — unlimited vocabulary and grammar
  • Fast-paced — build complex sentences from the start
  • Unforgettable — efficient spaced repetition system
  • AI tutor to answer your grammar questions