Learn Hardcore Croatian: Kad budeš u gradu, nazovi me. - When you are in the city, call me.

They mean the same thing: kad is just a shorter, very common form of kada. Both are fine in speech and writing. Kada can feel a bit more formal or emphatic, but there’s no change in meaning.

Why is it budeš and not ćeš biti after kad?

In Croatian, future time in clauses introduced by kad is normally expressed with the present (often the budem/budeš set of biti) or with Future II, not with ću/ćeš + infinitive. So you say Kad budeš u gradu…, not ✗Kad ćeš biti u gradu… in standard usage.

What exactly is budeš?

It’s the present tense (dependent/subjunctive-like) form of biti used in subordinate clauses referring to the future. Paradigm: budem, budeš, bude, budemo, budete, budu. Here, budeš = “you are (when/once you’re…)” in a future-time sense.

Could I say Kad si u gradu, nazovi me?

You can, but it changes the nuance. Kad si u gradu… suggests a general or habitual situation (“whenever you’re in town”). Kad budeš u gradu… points to a specific future occurrence (“when you’re in town (next time), call me”).

Why is it u gradu and not u grad?

Because u + locative (u gradu) expresses location (“in town”). u + accusative (u grad) expresses motion towards (“into town”). Compare: Idem u grad (“I’m going into town”) vs. Jesam u gradu (“I’m in town”).

Could I say Kad dođeš u grad, nazovi me? Is that different?

Yes, it’s fine. Kad dođeš u grad… focuses on the moment of arrival (“when you arrive in town”). Kad budeš u gradu… focuses on being there at some point (“when you’re in town”).

What does nazovi convey compared to zovi?

Nazovi is the imperative of the perfective verb nazvati, meaning “make a (single) call” (one completed action). Zovi is the imperative of the imperfective zvati, which can imply repeated or ongoing calling (“keep calling”/“call (in general)”). Here, nazovi me fits a one-time call.

Is nazovi really an imperative? How is it formed?

Yes. From the perfective infinitive nazvati (“to call”), the 2nd sg imperative is nazovi, 2nd pl is nazovite. So: Nazovi me (informal sing.), Nazovite me (plural or polite).

How do I make the sentence polite or formal?

Use the plural/formal address: Kad budete u gradu, nazovite me. You can add politeness markers: … molim vas or … molim Vas.

Where does me go? Can I say Me nazovi?

Me is the unstressed (clitic) accusative of ja (“me”). In imperatives it encliticizes after the verb: Nazovi me. Starting the clause with me is not idiomatic: ✗Me nazovi. For emphasis you can use the stressed form: Nazovi mene (“Call me (not someone else)”).

What about punctuation—why is there a comma?

When the subordinate clause comes first, you set it off with a comma: Kad budeš u gradu, nazovi me. If the main clause comes first, you normally don’t use a comma: Nazovi me kad budeš u gradu.

Could I drop me and just say Nazovi?

It’s grammatical but vague; it means “Make a call.” In real life you’d usually specify the object: Nazovi me (“Call me”) or name the person: Nazovi Marka.

Can I use Ako instead of Kad?

You can, but it changes meaning. Kad = “when” (it’s expected to happen). Ako = “if” (it may or may not happen). Ako budeš u gradu, nazovi me = “If you’re (happen to be) in town, call me.”

Is Kad budeš bio u gradu correct?

It’s grammatically possible (it uses Future II with biti: budeš bio), but with biti most speakers avoid the doubled form and simply say Kad budeš u gradu. Use the fuller Future II more naturally with other verbs: Kad budeš došao, nazovi me.

Can I change the main clause to future instead of imperative?

Yes: Nazvat ću te kad budeš u gradu. (or Kad budeš u gradu, nazvat ću te.) That states your future intention rather than giving an instruction.

How would I address multiple friends informally?

Use plural forms: Kad budete u gradu, nazovite me. (Same as the polite form; Croatian uses the same verb forms for plural and for formal address.) You can add molim vas for politeness if you like.