Nemam sitniša za kartu, pa ću platiti karticom.

Here, sitniš means small change — usually coins or low-value money.

So Nemam sitniša means I don’t have any change or I don’t have small change.

It works like English change, not like a countable word such as coins. That is why Croatian uses a singular noun here.

Sitniša is the genitive singular form of sitniš.

After nemati (to not have), Croatian often uses the genitive instead of the accusative, especially with:

• mass nouns
• indefinite amounts
• things understood as any / some

So nemam sitniša feels like I don’t have any change.

This is a very common pattern in Croatian. Compare:

• Imam vremena. = I have time.
• Nemam vremena. = I don’t have time.
• Nemam novca. = I don’t have money.

So in this sentence, sitniša is very natural and standard.

They are related words, but they do not mean the same thing here.

• karta = ticket (also sometimes map or playing card, depending on context)
• kartica = card, especially a bank card / payment card

So in this sentence:

• za kartu = for the ticket
• karticom = by card / with a card

This is important because English learners may see both words and assume they are the same. In this sentence, they are two different things:

• the thing being paid for = karta
• the payment method = kartica

Za takes the accusative here, and kartu is the accusative singular of karta.

• nominative: karta
• accusative: kartu

In this sentence, za kartu means for the ticket.

That can mean:

• money needed to buy the ticket, or
• money needed to pay for the ticket

So Nemam sitniša za kartu is literally something like I don’t have change for the ticket.

Here, pa means so, and so, or therefore.

It connects the two parts of the sentence:

• Nemam sitniša za kartu = I don’t have change for the ticket
• pa ću platiti karticom = so I’ll pay by card

So pa introduces the result or consequence.

It is very common in everyday Croatian and sounds natural in speech. In many contexts, it is a bit more conversational than a more formal connector like stoga or zato.

Yes. Ću platiti is the future tense.

Croatian forms the future with:

• a short form of htjeti (ću, ćeš, će...)
• plus the infinitive

So:

• ću platiti = I will pay

In this sentence:

• pa ću platiti karticom = so I’ll pay by card

A useful thing to know: ću is a clitic, so it usually goes near the beginning of the clause, in second position. Because the clause starts with pa, the next thing is ću:

• pa ću platiti...

You can also see:

• Platit ću karticom.
• Ja ću platiti karticom.

Those are also future forms, just with different word order.

Karticom is the instrumental singular of kartica.

• nominative: kartica
• accusative: karticu
• instrumental: karticom

The instrumental is often used to show the means or instrument used to do something.

So:

• platiti karticom = to pay by card
• literally: to pay with a card

This is the same idea as:

• pisati olovkom = to write with a pencil
• putovati vlakom = to travel by train
• platiti gotovinom = to pay in cash

So karticom answers the question how / by what means?

Croatian often leaves out subject pronouns because the verb already shows the person.

Here:

• nemam already means I do not have
• ću also shows I will

So ja is not necessary.

Croatian includes ja only when it is useful for:

• emphasis
• contrast
• clarification

For example:

• Ja nemam sitniša, ali on ima. = I don’t have change, but he does.

Without emphasis, leaving out ja is completely normal and natural.

Platiti is the perfective verb, and plaćati is the imperfective one.

In this sentence, the speaker means one complete future action:

• I’ll pay by card

That is why platiti is the natural choice.

Very roughly:

• platiti = to pay, as a completed act
• plaćati = to be paying / to pay repeatedly / to pay in general

So:

• Platit ću karticom. = I’ll pay by card.
• Plaćam karticom. = I pay by card / I am paying by card.
• Uvijek plaćam karticom. = I always pay by card.

In this sentence, the speaker is talking about one decision in one situation, so platiti fits best.

Yes, Croatian word order is fairly flexible, although some versions sound more natural than others.

The original sentence:

• Nemam sitniša za kartu, pa ću platiti karticom.

A few possible variations:

• Nemam sitniša za kartu, pa platit ću karticom. → this is much less natural here
• Nemam sitniša za kartu, pa ću karticom platiti. → possible, but marked
• Nemam sitniša za kartu. Platit ću karticom. → very natural

The original version is good because:

• it sounds natural
• it keeps the clitic ću in a normal position
• it puts karticom at the end, where the payment method gets natural focus

So yes, Croatian allows variation, but the original sentence is a very idiomatic way to say it.