Kedua pihak sudah setuju.

Kedua means both or the two in this sentence. So kedua pihak means both parties.

By contrast, dua pihak usually just means two parties as a number, without emphasizing that you mean both of them together.

• kedua pihak = both parties
• dua pihak = two parties

So in this sentence, kedua is the more natural choice.

Because the meaning changes.

• kedua pihak = both parties
• pihak kedua = the second party

This is a very important word-order difference in Indonesian. When kedua comes before the noun, it often means both/the two. When kedua comes after the noun, it usually means second.

So:

• Kedua pihak sudah setuju. = Both parties have agreed.
• Pihak kedua sudah setuju. = The second party has agreed.

Pihak means side, party, or one side involved in a matter, especially in formal, legal, political, or negotiation contexts.

In kedua pihak, it refers to the two sides or parties involved in an agreement, dispute, discussion, or contract.

Examples:

• kedua belah pihak = both sides / both parties
• pihak pemerintah = the government side
• pihak sekolah = the school side

It sounds more formal than just talking about orang or mereka.

Sudah shows that the action or state has already happened or is already true.

So:

• Kedua pihak setuju. = Both parties agree / are in agreement.
• Kedua pihak sudah setuju. = Both parties have already agreed / are already in agreement.

In English, this may be translated with already, have, or sometimes just simple present depending on context.

Yes, usually you can.

• Kedua pihak sudah setuju.
• Kedua pihak telah setuju.

Both are understandable and similar in meaning. However:

• sudah is very common in everyday speech and writing
• telah sounds more formal or written

In many formal contexts, though, a more natural phrasing might be:

• Kedua pihak telah menyetujui hal tersebut. = Both parties have agreed to that / approved that.

That is because setuju often describes being in agreement, while menyetujui more clearly means to approve or to agree to something.

It behaves a lot like an adjective meaning in agreement or agreeable, but in English it is often translated with the verb agree.

So sudah setuju literally feels like already in agreement.

That is why Indonesian can say:

• Saya setuju. = I agree.
• Mereka tidak setuju. = They do not agree.
• Kami sudah setuju. = We have already agreed / We are already in agreement.

So even if English uses a verb, Indonesian learners should remember that setuju often acts like a stative predicate.

This is a very common learner question.

• setuju = to agree / to be in agreement
• menyetujui = to approve something / to agree to something

Compare:

• Saya setuju. = I agree.
• Saya setuju dengan usulan itu. = I agree with that proposal.
• Saya menyetujui usulan itu. = I approve that proposal / I agree to that proposal.

In your sentence, setuju works well because the focus is on the state of agreement between the two parties.

Indonesian does not use auxiliary verbs like English have in the same way.

English says:

• Both parties have agreed.

Indonesian says:

• Kedua pihak sudah setuju.

The idea of completion or prior occurrence is expressed by sudah, not by a separate verb like have.

This is normal in Indonesian. Tense is often shown through context or particles like:

• sudah = already
• belum = not yet
• sedang = in progress
• akan = will

Yes, depending on context, it can be understood a few slightly different ways in English:

• Both parties have agreed
• Both parties already agree
• Both parties are in agreement

Because Indonesian does not mark tense the same way English does, translation depends on the situation. The word sudah strongly suggests that agreement has already been reached, so have agreed is often the best translation.

Both are used, and both mean both parties / both sides.

• kedua pihak = both parties
• kedua belah pihak = both sides / both parties

Kedua belah pihak sounds a little fuller and is very common in formal or legal language. Kedua pihak is slightly shorter but still very natural.

So your sentence could also be:

• Kedua belah pihak sudah setuju.

This means essentially the same thing.

Yes.

• Kedua pihak setuju.

This is grammatical and natural. Without sudah, the sentence is a bit more neutral and can mean:

• both parties agree
• both parties are in agreement

Adding sudah makes it clearer that the agreement has already been reached.

It is fairly neutral and slightly formal because of the word pihak.

• pihak is common in formal, professional, legal, business, and news contexts
• sudah is neutral and common in everyday language

So the whole sentence sounds natural in many situations, especially when talking about negotiations, contracts, disputes, or official discussions.

Yes, and it is very natural.

• Kedua pihak sudah setuju.
• Kedua pihak telah sepakat.

Both mean something like Both parties have agreed.

There is a slight nuance:

• setuju = agree
• sepakat = reach an agreement / be in mutual agreement

Sepakat often sounds especially suitable when two sides have come to a shared decision. It is very common in news and formal contexts.