Compare o gasto essencial com o gasto supérfluo.

Compare is the imperative form, used to give an instruction or command: Compare ...

In Brazilian Portuguese, this form can sound:

• formal
• neutral/instructional
• common in textbooks, exercises, manuals, and written directions

Here it is most naturally understood as a command like Compare ...

If you wanted a more informal command to one person, you would often hear:

• Compara o gasto essencial com o gasto supérfluo.

If you wanted to address you formally, Compare is exactly right.

O is the masculine singular definite article, meaning the.

So:

• o gasto essencial = the essential spending/expense
• o gasto supérfluo = the superfluous spending/expense

Portuguese usually uses articles more often than English does, especially before nouns in general statements or instructional contexts. Repeating the article before the second noun phrase makes the comparison clearer and more balanced.

Here, gasto is a noun, not a verb.

It means something like:

• spending
• expense
• expenditure

It comes from the verb gastar (to spend), but in this sentence it functions as a thing, not an action.

So:

• Eu gasto dinheiro = I spend money → gasto is a verb
• O gasto é alto = The spending/expense is high → gasto is a noun

In your sentence, both instances of gasto are nouns.

The verb comparar is commonly used with com when you compare one thing with another:

• comparar X com Y = to compare X with Y

So:

• Compare o gasto essencial com o gasto supérfluo.

This is a very standard pattern in Portuguese.

You may also sometimes see comparar X a Y, but comparar ... com ... is extremely common and usually the safest choice for learners.

In Portuguese, adjectives often come after the noun.

So:

• gasto essencial = essential spending
• gasto supérfluo = superfluous spending

English often puts adjectives before the noun, but Portuguese frequently places them after it.

Could they come before the noun? Sometimes adjective position can change for style or emphasis, but in this sentence the normal, natural order is:

• gasto essencial
• gasto supérfluo

Because Portuguese adjectives behave differently depending on their endings.

• essencial ends in -al, so its masculine and feminine singular forms are the same:

  • gasto essencial
  • despesa essencial

• supérfluo ends in -o, so it changes:

  • masculine singular: supérfluo
  • feminine singular: supérflua

Examples:

• o gasto supérfluo
• a despesa supérflua

So the adjective must agree with the noun in gender and number.

They are singular because the sentence is talking about the category or type of spending, not individual expenses.

So:

• o gasto essencial = essential spending as a concept/category
• o gasto supérfluo = unnecessary spending as a concept/category

Portuguese often uses the singular this way, just as English can say:

• Compare essential spending with unnecessary spending

If you wanted to talk about multiple specific expenses, you might use the plural:

• Compare os gastos essenciais com os gastos supérfluos.

Yes, supérfluo is a real and useful word, but it sounds a bit more formal or elevated than some everyday alternatives.

It means:

• superfluous
• unnecessary
• nonessential

A more everyday alternative might be:

• desnecessário

So these are similar:

• gasto supérfluo
• gasto desnecessário

However, supérfluo is perfectly natural in writing, educational material, finance-related language, or more formal speech.

The stress is on pér:

• su-PÉR-flu-o

This word has a written accent: é, which shows the stressed syllable.

A rough English-friendly guide is:

• soo-PAIR-floo-oh

But remember that Portuguese sounds are not exactly the same as English ones.

Also, supérfluo has four syllables:

• su-pér-flu-o

No, that would not sound natural here.

After com, you need a full noun phrase if you are contrasting two types of spending:

• Compare o gasto essencial com o gasto supérfluo.

You could omit the repeated noun only if the structure were changed in a natural way, but com supérfluo by itself does not work well because supérfluo is just an adjective here, not a full noun phrase.

So for learners, the best version is definitely:

• Compare o gasto essencial com o gasto supérfluo.

Overall, it sounds neutral to formal.

Why?

• Compare is a formal/instructional imperative form.
• supérfluo is slightly more formal vocabulary.
• The whole sentence sounds like something from:
  • a workbook
  • a budgeting guide
  • a financial literacy lesson
  • an exam or exercise

In everyday casual speech, someone might say something simpler, such as:

• Compara o que é essencial com o que é supérfluo.
• Compare os gastos essenciais com os desnecessários.

But your original sentence is perfectly correct and natural in a written instructional context.