Adverbs of Quantity | Portuguese (Brazil) Grammar

Adverbs of quantity (also called adverbs of degree or intensity) answer how much? — how tired, how expensive, how often. They turn the dial up or down on a verb, an adjective, or another adverb: muito caro (very expensive), pouco provável (unlikely), meio cansada (kind of tired). The single most important fact about all of them is that as adverbs they are invariable — and several of these words also have a determiner life where they do agree, which is exactly where learners stumble.

The core quantity adverbs

Portuguese	English	Portuguese	English
muito	very, a lot	tão	so (as in "so tall")
pouco	little, not very	quase	almost
mais	more	apenas / só	only, just
menos	less	somente	only (more formal)
bastante	quite, fairly	bem	really, quite (informal)
demais	too much	meio	somewhat, kind of

Esse restaurante é muito caro.

This restaurant is very expensive.

É pouco provável que ele venha.

It's unlikely that he'll come.

All invariable as adverbs

Because these words modify adjectives, verbs, and other adverbs — never nouns — they freeze. This is the rule from the overview page, applied to degree. Watch muito stay muito even when the adjective beside it is feminine plural:

Elas estão muito cansadas.

They are very tired.

As provas foram muito difíceis.

The exams were very hard.

Cansadas and difíceis agree with their nouns, but muito does not — it is describing the adjective, so it is locked.

The determiner trap: when they DO agree

Here is the subtlety. Several of these words have a second job as quantifiers / determiners, where they sit before a noun and tell you how many / how much. In that role they are no longer adverbs — they are determiners, and determiners agree.

Tem muitas pessoas aqui.

There are a lot of people here.

Ela comprou poucos livros.

She bought few books.

Compare directly:

muito caro (adverb, before adjective → invariable) vs muitos carros (determiner, before noun → agrees)
pouco provável (adverb → invariable) vs poucas vezes (determiner → agrees)
bastante interessante (adverb → invariable) vs bastantes pessoas (determiner → agrees, in careful usage)

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The decision rule is the same as for any of these words: look at what comes right after. Noun → it's a determiner, make it agree (muitos amigos). Adjective, adverb, or verb → it's an adverb, freeze it (muito legal, muito bem, gosto muito). The word doesn't change meaning much; only its grammatical behavior flips.

meio: the classic invariability trap

Meio used as a degree adverb means "somewhat / kind of / a bit," and as an adverb it is invariable — even when it sits in front of a feminine or plural adjective. This is the single most common agreement error in the whole topic, because the -o ending screams "masculine" to a learner's eye, and they want to "fix" it to match a feminine subject.

Ela tá meio cansada hoje.

She's kind of tired today.

As crianças ficaram meio assustadas.

The kids got a bit scared.

In both, the adverb is meio, not meia and not meios — even though cansada and assustadas are feminine/plural. Meio here means "somewhat," and as a degree adverb it never moves.

Contrast this with meio/meia used as an adjective or noun meaning "half," where it does agree:

Quero meia porção, por favor.

I'd like a half portion, please.

Já é meia-noite e meia.

It's already half past midnight.

So meia porção (half a portion — adjective, agrees) but meio cansada (somewhat tired — adverb, frozen). The phrase meia-noite e meia even shows both: meia agreeing with noite.

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Memorize one model sentence to anchor the rule: Ela tá meio cansada — "She's kind of tired." If you can produce this with meio (not meia) automatically, you have beaten the trap. The test: if you can swap in "somewhat/kind of," it's the invariable adverb; if you can swap in "half," it's the agreeing adjective.

bem and demais: the colloquial intensifiers

In informal Brazilian speech, bem doubles as "really / quite," intensifying an adjective much like muito:

Esse forró tá bem legal!

This forró party is really cool!

O café aqui é bem forte.

The coffee here is really strong.

Demais literally means "too much / excessively," but in colloquial Brazilian it has flipped into a positive intensifier meaning "amazing / awesome," depending on tone:

Essa praia é linda demais!

This beach is gorgeous (lit. beautiful to excess / amazingly beautiful)!

Você comeu demais, vai passar mal.

You ate too much, you're going to feel sick.

The first is the colloquial "awesome" sense (positive); the second is the literal "excessively" sense. Tone and context do the disambiguating. Both uses are invariable.

tão and tanto: "so" and "so much"

These two are easy to confuse. Tão modifies an adjective or adverb ("so + quality"); tanto modifies a verb or noun ("so much / so many"). Tanto agrees when it functions as a quantifier before a noun (tantas pessoas); tão is always invariable.

Por que você tá tão nervoso?

Why are you so nervous?

Eu te amo tanto.

I love you so much.

Tinha tanta gente na rua!

There were so many people in the street!

Common Mistakes

❌ Ela tá meia cansada.

Incorrect — as the adverb 'somewhat', meio is invariable; it stays 'meio'.

✅ Ela tá meio cansada.

She's kind of tired.

❌ As casas são muitas caras.

Incorrect — before an adjective 'muito' is an adverb and must stay invariable.

✅ As casas são muito caras.

The houses are very expensive.

❌ Por que você tá tanto nervoso?

Incorrect — before an adjective use 'tão', not 'tanto'.

✅ Por que você tá tão nervoso?

Why are you so nervous?

❌ Ela comprou muito livros.

Incorrect — before a noun 'muito' is a determiner and must agree: 'muitos'.

✅ Ela comprou muitos livros.

She bought a lot of books.

The meia cansada error is so widespread that it is worth one final emphasis: the -o in meio is not a masculine ending here, it is the frozen adverb. The moment meio means "somewhat," it stops agreeing with anything, period. The fourth pair is the mirror-image error: when muito really is before a noun, learners sometimes "forget" to agree it. The full decision rests on one question — what is the word modifying — and once you reflexively check that, both errors disappear.

Key Takeaways

Degree/quantity adverbs (muito, pouco, bastante, meio, tão, demais, bem) are invariable when modifying adjectives, adverbs, or verbs.
Several of them flip to agreeing determiners before a noun: muito caro (adverb) vs muitos carros (determiner).
meio = "somewhat" is invariable (ela tá meio cansada); only meio/meia = "half" agrees.
tão modifies adjectives/adverbs ("so"); tanto modifies verbs/nouns ("so much/many").
Colloquially, bem = "really" and demais = "awesome / too much."

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