Learn Hardcore Croatian: Ako kasnimo, stići ćemo na sljedeći vlak. - If we are late, we will make the next train.

Croatian normally uses the present tense in conditional clauses referring to the future. So Ako kasnimo is the standard way to say “If we are late (in the future)…”. A more formal alternative is Ako budemo kasnili (Future II), but using future I here is not used: avoid Ako ćemo kasniti.

Can I say Ako ćemo kasniti?

No. For future conditions, Croatian uses:

Present: Ako kasnimo…
Future II (formal): Ako budemo kasnili… Using future I in the if-clause (Ako ćemo kasniti) is considered incorrect or very nonstandard in this meaning.

What’s the difference between kasniti and zakasniti?

kasniti (imperfective): “to be late” as an ongoing state or habit. Example idea: Ako kasnimo (na ovaj vlak)…
zakasniti (perfective): “to be late/arrive late (and miss something)” as a completed one-time event. Very natural here: Ako zakasnimo (na ovaj vlak), uhvatit ćemo sljedeći.

How is the future tense formed in stići ćemo?

Croatian Future I = infinitive + clitic forms of htjeti:

ću, ćeš, će, ćemo, ćete, će Examples:
Stići ćemo na sljedeći vlak.
With subject for emphasis: Mi ćemo stići…
Negative: Nećemo stići…
Yes/no question: Hoćemo li stići…?

Why is it stići ćemo and not ćemo stići?

Because ćemo is a clitic (unstressed word) and must appear in “second position” in the clause. It cannot start a clause by itself. Acceptable options are:

Stići ćemo…
Mi ćemo stići…
Na sljedeći vlak ćemo stići… But not: Ćemo stići…

Why is the preposition na used with vlak? What case is sljedeći vlak?

With motion toward/catching scheduled transport, Croatian uses na + accusative:

stići na vlak = arrive in time for the train (to catch it)
na sljedeći vlak is accusative. For inanimate masculine nouns like vlak, nominative and accusative look the same, so you see vlak (not “vlaka”). The adjective sljedeći is also in masculine accusative, which has the same form as nominative.

Could I use u sljedeći vlak or do sljedećeg vlaka instead of na sljedeći vlak?

u + accusative with verbs of entering (e.g., ući u vlak) means “into the train.” With stići, u vlak is not idiomatic.
do + genitive (e.g., do sljedećeg vlaka) means “up to” or “as far as,” not “catch.”
So for this meaning, stick with na sljedeći vlak, or use a different verb: uhvatiti sljedeći vlak.

Is stići the best verb here, or should I use uhvatiti?

Both are fine, with a nuance:

stići (na vlak): “to make it in time for the train” (arrive in time).
uhvatiti (vlak): “to catch the train” (most straightforward, very common).
So you could also say: Ako kasnimo, uhvatit ćemo sljedeći vlak.

Can I drop the preposition and say stići ćemo sljedeći vlak?

No. stići doesn’t take a direct object like that. Use:

stići na (vlak/let/… )
or switch to a transitive verb: uhvatiti (vlak).

Is the comma necessary after the if-clause?

Yes. When the ako-clause comes first, use a comma:

Ako kasnimo, stići ćemo na sljedeći vlak. If the main clause comes first, a comma is usually not written:
Stići ćemo na sljedeći vlak ako kasnimo.

Can I change the word order in the main clause?

Yes, Croatian word order is flexible for emphasis, but keep clitics in second position:

Neutral: Stići ćemo na sljedeći vlak.
Emphasizing the destination: Na sljedeći vlak ćemo stići.
Emphasizing the subject: Mi ćemo stići na sljedeći vlak.

Do I need to say the subject pronoun mi?

Not usually. The form ćemo already shows “we.” Use mi only for emphasis or contrast:

Neutral: Stići ćemo…
Emphatic/contrasting: Mi ćemo stići… (a oni možda neće).

What’s the difference between sljedeći and sledeći, and between vlak and voz?

sljedeći and vlak are standard Croatian.
sledeći and voz are standard Serbian.
Stick to one standard in a sentence: in Croatian, prefer sljedeći vlak.

How do I pronounce the letter ć in stići and ćemo?

ć is a soft “ch,” shorter and lighter than č.
Approximate English guide:
ć ≈ the “t” + “y” sound in “got you” said quickly (“gotcha”), but softened. So: stići ≈ “STEE-chy,” ćemo ≈ “CHEH-mo.”

Why perfective stići and not the imperfective stizati?

stići (perfective) = a single, completed arrival/making it (fits one-time future plans).
stizati (imperfective) = ongoing/repeated arriving.
Use stizat ćemo only for habitual/repeated situations: Ako često kasnimo, stizat ćemo samo na sljedeći vlak.
Note: In if-clauses you may also see perfective present for future meaning: Ako ne stignemo na ovaj vlak, uhvatit ćemo sljedeći.