Gdy mam czas, idę do biblioteki.

When I have time, I go to the library.

Breakdown of Gdy mam czas, idę do biblioteki.

• ja: I
• mieć: to have
• iść: to go
• do: to
• czas: the time
• biblioteka: the library
• gdy: when

Questions & Answers about Gdy mam czas, idę do biblioteki.

Why is gdy used here and can I use kiedy instead?

Both gdy and kiedy mean “when” in Polish.

• gdy is slightly more formal/literary and often appears in written or narrative contexts.
• kiedy is a bit more colloquial and common in speech.
  In this sentence you can freely swap them: Gdy mam czas, idę do biblioteki. = Kiedy mam czas, idę do biblioteki. No change in meaning.

Why is there a comma after Gdy mam czas?

Polish punctuation rules require a comma between a subordinate clause and the main clause.

• When the time-clause (Gdy mam czas) comes first, you always place a comma before the main clause (idę do biblioteki).
• If you reversed them, you’d still need a comma: Idę do biblioteki, gdy mam czas.

Why isn’t the subject pronoun ja (I) used before mam or idę?

Polish verb endings already tell you the person and number.

• mam is first person singular (“I have”),
• idę is first person singular (“I go/am going”).
  Adding ja is grammatically correct but redundant: Ja mam czas, ja idę do biblioteki is unusual unless you want to emphasize “I” specifically.

What tense and person is mam? Why isn’t czas declined differently?

• mam is the present tense, first person singular of mieć (“to have”).
• czas here is the direct object of mieć, so it takes the accusative. However, czas has the same form in nominative and accusative (czas), so you don’t see a visible change.

What’s the difference between idę and chodzę, and why is idę used in this sentence?

They are both imperfective verbs meaning “to go,” but with different aspectual/usage nuances:

• iść (present idę) is directional: “I’m going (right now/toward a place).”
• chodzić (present chodzę) is nondirectional or habitual: “I go (regularly).”
  In your sentence idę suggests a simple statement “when I have time, I go to the library,” and it’s perfectly idiomatic. If you wanted to stress the routine aspect, you could say chodzę do biblioteki, but idę is also common for repeated actions.

Why is biblioteki in the genitive case?

The preposition do always governs the genitive case. After do you change the noun to genitive:

• biblioteka (nominative) → biblioteki (genitive).
  Thus idę do biblioteki = “I go to the library.”

Can I switch the clause order to Idę do biblioteki, gdy mam czas? Does that affect meaning or punctuation?

Yes, you can:

• Gdy mam czas, idę do biblioteki.
• Idę do biblioteki, gdy mam czas.
  Meaning stays the same. In both cases you need a comma before the subordinate time-clause. The emphasis slightly shifts: leading with Gdy highlights the condition, while leading with Idę highlights the action.