mais + Adjective + do que

To compare two entities in Portuguese, follow these steps:

1. The Adverb: Use mais. It never changes its form.
2. The Adjective: Place the adjective after mais. The adjective must agree in gender and number with the first entity (or subject).
3. The Connector: Use que or do que. Both mean 'than' and are generally interchangeable before nouns or pronouns. However, do que is syntactically preferred or obligatory when the second part of the comparison is a full clause with a verb.

Important Note on Irregulars:
Four common adjectives usually use special one-word forms instead of 'mais + adjective' when comparing two different things:

• bom → melhor (better)
• mau → pior (worse)
• grande → maior (bigger)
• pequeno → menor (smaller)

These irregular forms must agree in number with the subject (e.g., melhores, piores, maiores, menores), but they are invariable in gender, meaning they use the exact same form for masculine and feminine. Additionally, in Brazilian Portuguese menor is frequently used to mean 'younger' when referring to age (e.g., meu irmão menor = my younger brother); in European Portuguese, mais novo is far more common for 'younger', since 'menor' there usually implies smaller size rather than age. For 'older', mais velho is the clearest and most widely understood choice in both varieties. 'Maior' is sometimes used colloquially in Brazil to mean 'older' (e.g., meu irmão maior) and is grammatical, but it is far less common than 'mais velho' and can be ambiguous with size.

Comparing to a Number: When comparing to a specific number or quantity rather than another noun, replace que/do que with mais de (or menos de). For example, Ele tem mais de vinte anos (He is more than twenty years old) — not mais que vinte anos. This is a common trap for English speakers, since English uses 'more than' for both types of comparison.

Exceptions to the Rule:
• Comparing Qualities: If you are comparing two qualities of the same person or thing, you must use 'mais + adjective' (e.g., 'Ele é mais bom do que inteligente' — He is kind rather than smart, or 'A sala é mais grande do que confortável' — The room is big rather than comfortable).
• Past Participles: The adverbs bem (well) and mal (badly) also share the irregular comparatives melhor and pior. However, when modifying a past participle acting as an adjective, it is the required standard to use mais bem or mais mal instead of melhor or pior (e.g., 'mais bem preparado', 'mais mal informado'). Using melhor or pior in this context is considered a grammatical error.
• Regional Usage & Warnings: In European Portuguese, mais pequeno is very common and often preferred over 'menor' when talking about physical size, though 'menor' is still used for abstract concepts (e.g., um problema menor), age, or mathematical quantities. However, learners focusing on Brazilian Portuguese should exclusively use menor, as mais pequeno is highly stigmatized and widely considered incorrect by native speakers. Furthermore, while mais grande is correct when comparing two qualities of the same entity, it is strictly incorrect when comparing the physical size of two different entities; in that case, you must always use maior.