Learn Hardcore Croatian: Ispričat ću ti priču sutra.

Word order-wise, Croatian doesn’t require ću to come directly after the subject like English does. Instead, ću is a clitic, and clitics tend to appear very early in the sentence (so-called “second position”). In this sentence, the verb comes first, then the clitics:

Ispričat (main verb) + ću ti (clitics) + priču sutra (rest of the sentence)

Why isn’t ja (I) used in the sentence?

Croatian is a pro-drop language: it usually omits subject pronouns because the verb form already shows who the subject is.

Ispričat ću ti priču sutra.
The ću form already says it’s 1st person singular → “I will”.

You can add ja for emphasis or contrast:

Ja ću ti ispričati priču sutra. – I will tell you a story tomorrow (as opposed to someone else).

But in a neutral sentence, ja is usually left out.

What exactly does ću mean here?

Ću is the 1st person singular present tense of the verb htjeti (to want), but in modern Croatian it’s mainly used as a future tense auxiliary, not with its original meaning of “want” in this structure.

In this pattern:

ću + infinitive = will + verb

So:

ispričat ću ≈ I will tell
napisat ću ≈ I will write
kupit ću ≈ I will buy

Outside of the future tense construction, htjeti can still mean “to want”, but then it’s usually used differently (e.g. hoću ići – I want to go).

Why is it ispričat ću and not ispričati ću?

This is a standard spelling rule for Croatian Future I:

When the auxiliary (ću, ćeš, …) comes after the infinitive, the infinitive loses the final -i:

ispričati ću → ispričat ću
napisati ću → napisat ću
čitati ću → čitat ću

Writing ispričati ću is considered non‑standard/incorrect in contemporary Croatian.

When the auxiliary comes before the infinitive, the infinitive keeps the full form:

Ja ću ispričati priču.
Sutra ću ti ispričati priču.

So both are correct:

Ispričat ću ti priču.
Ja ću ti ispričati priču.

But not: Ispričati ću ti priču.

What does ti mean, and why is it in that position?

In this sentence, ti is:

the dative singular of the pronoun ti (you, singular, informal),
used as an indirect object: to you / for you.

So literally, the structure is:

Ispričat ću ti priču sutra.
→ I will tell (to you) a story tomorrow.

Ti here is also a clitic pronoun, so it tends to appear right after other clitics and early in the sentence. That’s why we get the clitic cluster:

Ispričat
- ću ti
  - priču sutra

Other acceptable orders (with slightly different emphasis) include:

Sutra ću ti ispričati priču.
Ja ću ti sutra ispričati priču.

But you cannot normally move ti freely to the very end:

✗ Ispričat ću priču sutra ti. (unnatural / wrong)

Is ti here the same as ti meaning “you” as a subject?

It’s the same pronoun, but in a different case and role:

Ti si moj prijatelj. – ti = you (subject, nominative)
Ispričat ću ti priču. – ti = to you (indirect object, dative)

So:
ti (nom.) = you
ti (dat.) = to you / for you

What form is priču, and why does it end in -u?

Priču is:

the accusative singular of priča (story),
used as the direct object of the verb ispričati (to tell (a story)).

Declension of priča (singular, main forms):

Nominative: priča – a story (subject)
Genitive: priče
Dative: priči
Accusative: priču – a story (object)
Locative: priči
Instrumental: pričom

Because it is the thing being told, priča appears in the accusative, which for this noun is priču.

What is the difference between ispričati and pričati?

This is about aspect, which is very important in Croatian verbs:

pričati – to tell, to talk, to be telling (imperfective)
- focuses on the ongoing process, no guarantee of completion.
- e.g. Pričam ti priču. – I’m telling you a story (right now).
ispričati – to tell (a story) completely (perfective)
- focuses on the completed action / result.
- e.g. Ispričat ću ti priču. – I will (finish) telling you a story.

For future tense, if you want to emphasize that the action will be completed, you typically use the perfective:

Ispričat ću ti priču sutra. – I will (fully) tell you a story tomorrow.

If you used pričati in the future (e.g. Pričat ću ti priču sutra.), the idea is more about the activity of telling that will be happening, less about its completion.

Can I change the position of sutra? Does the meaning change?

Yes, sutra (tomorrow) is an adverb of time and is fairly flexible. All of these are grammatically correct:

Ispričat ću ti priču sutra.
Sutra ću ti ispričati priču.
Ispričat ću ti sutra priču.

The basic meaning (I’ll tell you a story tomorrow) stays the same, but emphasis can shift:

Sutra ću ti ispričati priču.
→ strong focus on tomorrow (as opposed to today, for example).
Ispričat ću ti priču sutra.
→ more neutral; just adds when at the end.

In practice, all three are very natural; the difference is subtle and often just stylistic.

Could I say Reći ću ti priču sutra instead of Ispričat ću ti priču sutra?

Not really. Reći means to say or to tell (a fact, a sentence), and it does not normally take priču (a story) as its object that way.

Better options:

Reći ću ti nešto sutra. – I’ll tell you something tomorrow.
Ispričat ću ti priču sutra. – I’ll tell you a story tomorrow.

For telling a story, (is)pričati priču is the natural collocation:

pričati priču / ispričati priču = to tell a story

Can I leave out ti and just say Ispričat ću priču sutra?

Yes, grammatically you can:

Ispričat ću priču sutra. – I’ll tell a story tomorrow.

Now the sentence doesn’t say who will hear the story. In many contexts that’s fine. But if you specifically want to say to you, then ti is needed:

Ispričat ću ti priču sutra. – I’ll tell you a story tomorrow.

So omitting ti changes the meaning slightly (removing the indirect object).

Could I also say Ispričat ću ti jednu priču sutra? What’s the difference?

You can, and it’s natural:

Ispričat ću ti priču sutra.
Ispričat ću ti jednu priču sutra.

Adding jednu (feminine form of jedan, one) can have two common effects:

It can sound like “a story” / “one (particular) story”, making it a bit more specific or slightly more informal / conversational.
In some contexts, it can emphasize that it’s one story (not several).

In everyday speech, both versions are very commonly used with almost the same meaning. The version without jednu is a bit more neutral.

Is this sentence formal or informal? Can I say it to anyone?

Because it uses ti (you singular, informal), the sentence is informal and suitable for:

friends,
family members,
children,
anyone you would naturally address with ti.

For a polite / formal version to one person, you’d use Vam (dative of Vi – formal you):

Ispričat ću Vam priču sutra. – I will tell you (polite) a story tomorrow.

To a group you address informally as vi (plural), you’d use vam in lowercase:

Ispričat ću vam priču sutra. – I’ll tell you (pl.) a story tomorrow.

Capital Vam is used in formal writing for politeness; vam (lowercase) is plural/informal or neutral.