Se a blusa não couber, vou experimentar aquela maior.

Because after se when Portuguese is talking about a possible future situation, it normally uses the future subjunctive.

So:

• Se a blusa não cabe = sounds wrong for this meaning
• Se a blusa não couber = If the blouse/top doesn’t fit

Here, couber is the future subjunctive form of caber (to fit).

This pattern is very common in Portuguese:

• Se eu tiver tempo... = If I have time...
• Se ele puder... = If he can...
• Se a blusa não couber... = If the blouse doesn’t fit...

So even though English just uses the present in if it doesn’t fit, Portuguese uses this special future-oriented form.

It comes from caber, which means to fit or to have enough room.

Examples of caber:

• A blusa cabe em mim. = The top fits me.
• Isso não cabe na mala. = That doesn’t fit in the suitcase.
• Não cabe mais nada aqui. = Nothing else fits here.

Caber is an irregular verb, which is why the form becomes couber in this sentence.

A few useful forms:

• infinitive: caber
• present: cabe
• preterite: coube
• future subjunctive: couber

Because the sentence is about a condition that may happen later, not about a fact already known.

In Portuguese, this is a standard structure:

• Se + future subjunctive, main clause with future meaning

So:

• Se a blusa não couber, vou experimentar aquela maior.

Literally, the structure is:

• If the top should not fit, I’m going to try that bigger one.

English usually just says if it doesn’t fit, but Portuguese marks that future uncertainty more explicitly.

This is especially common with verbs like:

• ser → for
• estar → estiver
• ter → tiver
• poder → puder
• fazer → fizer
• vir → vier

Because in Brazilian Portuguese, ir + infinitive is extremely common for talking about the future in everyday speech.

So:

• vou experimentar = I’m going to try on / I’ll try on
• experimentarei = I will try on

Both are grammatical, but vou experimentar sounds much more natural in normal conversation in Brazil.

This combination works very much like English going to or even simple will, depending on context.

Yes. In Brazilian Portuguese, experimentar can mean to try, to test, or to try on.

With clothes, it often means to try on:

• Vou experimentar a blusa. = I’m going to try on the top.

It can also be used in other situations:

• Quero experimentar esse doce. = I want to try that dessert.
• Vamos experimentar outro método. = Let’s try another method.

You may also hear provar for trying on clothes:

• Vou provar a blusa.

In Brazil, both are possible, but experimentar is very common and natural.

It means that bigger one.

The noun blusa is not repeated because it is understood from context.

So the full idea is:

• aquela blusa maior = that bigger top
• aquela maior = that bigger one

Portuguese often leaves out a noun when it is obvious:

• Quero a azul. = I want the blue one.
• Prefiro aquela menor. = I prefer that smaller one.
• Vou experimentar aquela maior. = I’m going to try that bigger one.

So aquela stands for that one, and maior describes it.

These are demonstratives, and they depend on how the speaker sees the item in relation to themselves.

Very roughly:

• esta = this
• essa = that
• aquela = that one over there / that more distant one

In real Brazilian Portuguese, esta is less common in everyday speech, and speakers often mostly use essa and aquela.

Here, aquela maior suggests the speaker is pointing to a specific larger one that feels more distant or separate:

• maybe one on another rack
• maybe one the salesperson is holding up
• maybe simply that one over there

So aquela is natural if the person is selecting from visible options.

Because maior is the normal comparative form of grande.

Just like in English:

• big → bigger
• grande → maior

So:

• blusa maior = bigger top
• mais grande = generally not the normal choice here

Other common irregular comparatives:

• bom → melhor = good → better
• mau → pior = bad → worse
• pequeno usually becomes menor in many contexts = smaller

Because Portuguese often omits a noun when it has just been mentioned and is easy to recover from context.

The sentence already mentions a blusa, so aquela maior naturally means:

• that bigger blouse/top
• or more naturally in English, that bigger one

This is very common with colors, sizes, and other descriptions:

• Quero a vermelha. = I want the red one.
• Ela comprou a mais barata. = She bought the cheaper one.
• Prefiro aquela menor. = I prefer that smaller one.

In Brazilian Portuguese, blusa is a fairly broad word for a women’s top or upper-body garment. Depending on context, it can mean something like:

• blouse
• top
• shirt
• sweater/light sweater

It does not always match the English word blouse perfectly.

So in a shopping context, blusa may simply refer to the garment the person is trying on, without needing a super precise English category.

Yes, the word order is natural, and yes, vou experimentar a maior is also possible in the right context.

Compare:

• vou experimentar aquela maior = I’m going to try that bigger one
• vou experimentar a maior = I’m going to try the bigger one

The difference is that aquela points to a specific item, almost like gesturing toward it. Without aquela, the phrase is more general and just means the bigger one.

So the original sentence feels like someone choosing among visible options.

A natural Brazilian pronunciation would sound roughly like:

• seh ah BLOO-zah naw koo-BER

A few notes:

• se sounds like seh
• blusa sounds like BLOO-zah
• não is nasal, something like naw̃
• couber has stress on the last syllable: cou-BER

In connected speech, it may sound smoother and more blended than this spelling suggests.

Possibly, depending on context.

Because blusa does not match one single English clothing word perfectly, translations can vary:

• If the blouse doesn’t fit, I’ll try that bigger one.
• If the top doesn’t fit, I’ll try that bigger one.
• If the shirt doesn’t fit, I’ll try that bigger one.

If the meaning has already been shown to the learner, the main grammar point is still the same regardless of which English clothing word was chosen.

Yes, but it depends on the meaning.

Use future subjunctive when the condition refers to a possible future event:

• Se a blusa não couber, vou experimentar outra.
• If the top doesn’t fit, I’ll try another one.

Use the present indicative after se when you mean something habitual or generally true:

• Se a blusa não cabe, eu peço outro tamanho.
• If the top doesn’t fit, I ask for another size.

That second example sounds more like a general habit or repeated situation, not one specific future case.

So in your sentence, couber is the right choice because the speaker is talking about what they will do next in this situation.