Semakin luas cakupannya, semakin tinggi preminya.

It is a very common Indonesian pattern meaning the more ..., the more ... or the X-er ..., the Y-er.

So this sentence expresses a proportional relationship:

• Semakin luas cakupannya — the broader the coverage
• semakin tinggi preminya — the higher the premium

It is used when a change in one thing goes together with a change in another.

Because each half of the comparison gets its own semakin.

• The first semakin introduces the first changing factor.
• The second semakin introduces the second changing factor.

This repetition is the normal pattern in Indonesian. It is the equivalent of English the more ..., the more ....

Indonesian often leaves out the verb to be in sentences like this.

So:

• cakupannya luas = its coverage is broad
• preminya tinggi = its premium is high

This is completely normal. Adjectives like luas and tinggi can act as predicates without any extra verb.

That is a very natural question.

In a basic noun phrase, adjectives usually do come after the noun:

• cakupan luas = broad coverage

But in this sentence, semakin luas cakupannya is not really a simple noun phrase. It is a clause-like structure in the semakin ... pattern, where the descriptive word often comes first.

You can think of it as being close in meaning to:

• cakupannya semakin luas

Both are natural, but semakin luas cakupannya fits the correlative pattern very smoothly and sounds idiomatic.

Cakupan means coverage, scope, or range.

In this context, because the sentence also uses premi, it almost certainly refers to insurance coverage.

The ending -nya makes it something like:

• the coverage
• its coverage

So cakupannya here means the coverage or its coverage, depending on how you want to understand the context.

Premi means premium, especially in financial or insurance contexts.

So preminya means:

• the premium
• its premium

In this sentence, it is very likely talking about an insurance premium.

-nya is a very flexible suffix in Indonesian. It can mean things like:

• his/her/its
• the
• something already known from context

In this sentence, -nya is best understood as referring to something already being discussed, so:

• cakupannya = the coverage / its coverage
• preminya = the premium / its premium

It does not necessarily mean a specific person like his or her here.

This is an important distinction.

• lebih means more in a simple comparison
• semakin means increasingly, or it helps build the the more ..., the more ... pattern

Compare:

• cakupannya lebih luas = its coverage is broader
• cakupannya semakin luas = its coverage is getting broader / increasingly broad
• semakin luas cakupannya, semakin tinggi preminya = the broader the coverage, the higher the premium

So lebih compares two things directly, while semakin suggests a rising degree or linked progression.

Yes. Makin is a common shorter form of semakin.

So you could also say:

• Makin luas cakupannya, makin tinggi preminya.

That sounds natural too, especially in less formal language.
Semakin is a bit more formal or neutral in writing.

Yes. For example:

• Kalau cakupannya lebih luas, preminya lebih tinggi.
• Cakupannya semakin luas, preminya semakin tinggi.

These are understandable and natural.

However, Semakin ..., semakin ... is especially good when you want to emphasize a general proportional rule, not just one specific case.

So the original sentence sounds very neat and idiomatic for expressing that relationship.

The comma is very helpful because it separates the two linked halves of the pattern:

• Semakin luas cakupannya, semakin tinggi preminya.

In careful writing, this punctuation is standard and makes the sentence easier to read.
Without the comma, people would probably still understand it, but the comma is better.

Indonesian nouns usually do not show singular or plural unless the context makes it clear.

So preminya here is best understood as a general singular idea:

• the premium

But depending on context, Indonesian often leaves number unspecified unless it really matters.

No, not at all. The pattern semakin ..., semakin ... is very general.

For example:

• Semakin lama, semakin sulit. — The longer it goes on, the harder it gets.
• Semakin banyak belajar, semakin paham. — The more you study, the more you understand.
• Semakin mahal barangnya, semakin tinggi kualitasnya. — The more expensive the item, the higher the quality.

So the structure is general; only the words cakupan and premi make this particular sentence sound like it is about insurance.