Dompet kecil saya muat di saku jaket saya.

Here muat means to fit or to have enough room.

So Dompet kecil saya muat di saku jaket saya means that the wallet is small enough to fit in the jacket pocket.

A useful contrast:

• muat = fit, be able to go into something because there is enough space
• masuk = go in, enter

So muat focuses on size and space, not just movement.

In Indonesian, the noun usually comes first, and words that describe it come after it.

So:

• dompet = wallet
• kecil = small
• saya = my

That gives:

• dompet kecil saya = my small wallet

A very common Indonesian pattern is:

noun + adjective + possessor

Examples:

• rumah besar saya = my big house
• buku baru saya = my new book

In this sentence, it means my small wallet.

That is because dompet kecil saya is a noun phrase:

• dompet = wallet
• kecil = small
• saya = my

If you want to say my wallet is small, Indonesian often uses:

• Dompet saya kecil.

So compare:

• dompet kecil saya = my small wallet
• dompet saya kecil = my wallet is small

Word order matters.

Because the sentence mentions two different possessed nouns:

• dompet kecil saya = my small wallet
• saku jaket saya = the pocket of my jacket / my jacket pocket

The second saya belongs to jaket, not to saku by itself.

So the structure is:

• saku jaket saya = pocket of my jacket

Indonesian often repeats possessive words where English might not need to.

Literally, it is:

• saku = pocket
• jaket = jacket
• saya = my

So saku jaket saya means the pocket of my jacket, or more naturally in English, my jacket pocket.

This is a very common Indonesian noun chain pattern:

noun + noun + possessor

Examples:

• pintu rumah saya = the door of my house / my house door
• warna mobil itu = the color of that car

Di is a preposition meaning in, at, or on, depending on context.

Here:

• di saku jaket saya = in my jacket pocket

Because the wallet fits in the pocket, di is the natural preposition.

Important note:

• di as a preposition is written separately: di saku
• di- as a passive prefix is written together with the verb: dibawa, ditulis

So di saku is correct because this di means location.

Yes, but the meaning changes slightly.

The original:

• Dompet kecil saya muat di saku jaket saya. means:
• My small wallet fits in my jacket pocket.

Possible alternatives:

• Dompet kecil saya masuk ke dalam saku jaket saya. = My small wallet goes into my jacket pocket / can go into my jacket pocket.
• Dompet kecil saya muat masuk ke saku jaket saya. = My small wallet fits into my jacket pocket.

So:

• muat emphasizes enough space
• masuk emphasizes going in

Indonesian does not normally use articles like English a, an, and the.

So:

• dompet can mean a wallet, the wallet, or just wallet, depending on context
• saku jaket saya can mean my jacket pocket or the pocket of my jacket

Context tells you how definite it is.

That is very normal in Indonesian.

Sometimes, yes, but saku is the more natural word for a clothing pocket.

• saku = pocket, especially in clothes
• kantong = bag, pouch, pocket, sachet, container; it is broader

So for jacket pocket, saku jaket is the best choice.

Examples:

• saku celana = pants pocket
• saku baju = shirt pocket

Yes, saya is neutral and polite. It is very common in standard Indonesian.

You could use aku in casual speech, especially with friends or in informal contexts:

• Dompet kecilku muat di saku jaketku.

That version sounds more informal and natural in everyday speech between close people.

Compare:

• saya = neutral, polite
• aku = casual, personal

Also notice that with aku, Indonesian often uses the suffix -ku:

• dompetku = my wallet
• jaketku = my jacket

You can, if the context already makes it obvious which jacket you mean. But without context, it sounds less specific.

Compare:

• di saku jaket saya = in my jacket pocket
• di saku jaket = in a jacket pocket / in the jacket pocket

So the original sentence is clearer because it explicitly says the jacket is yours too.

Yes, it is natural and grammatical.

It sounds like a straightforward statement meaning that the wallet is small enough to fit in the pocket.

A slightly more conversational version might also be:

• Dompet kecil saya muat di saku jaket.
• Dompet saya yang kecil muat di saku jaket saya.

But the original sentence is perfectly good Indonesian.

The structure is:

Subject + verb + location

Breaking it down:

• Dompet kecil saya = subject
• muat = verb
• di saku jaket saya = location phrase

So:

Dompet kecil saya / muat / di saku jaket saya
My small wallet / fits / in my jacket pocket

This is a very common Indonesian sentence pattern.