Accent Mark Rules

The single most useful idea about Portuguese accents is this: the accent marks the exception, not the rule. Portuguese words have a default stress position, and you write an accent precisely when a word breaks that default — or when an accent is needed to keep the spelling unambiguous. Learn the default first, then learn the three or four situations that override it, and you will accent correctly without memorizing word lists.

First, the vocabulary of stress

Every Portuguese word with two or more syllables has one stressed (tonic) syllable. Words are named by where that stress falls:

The default in Portuguese is paroxítona — most words are stressed on the second-to-last syllable, and most of those carry no accent (casa, caderno, janela, problema). The accent rules tell you when to override that silence.

Rule 1: Proparoxytones — ALWAYS accented

This is the easiest and most absolute rule. Every proparoxytone — every word stressed on the third-from-last syllable — carries a written accent. No exceptions.

More examples: ótimo, péssimo, número, lâmpada, fôlego, árvore, público, último. If you can hear that a word is stressed three syllables from the end, you know it must have an accent — the only question is acute or circumflex (acute for open vowels, circumflex for closed: médico vs. cômodo).

Rule 2: Oxytones — accented when they end in -a, -e, -o, -em, -ens

A word stressed on its last syllable takes an accent when it ends in one of these (with optional final -s):

• -a / -as: sofá, sofás, está, Pará
• -e / -es: café, cafés, você, jacaré, português
• -o / -os: avô, avós, paletó, cipó
• -em / -ens: também, parabéns, ninguém, armazéns, vinténs

Why these endings and not others? Because an oxytone ending in -a/-e/-o is the unexpected case — most words ending in those vowels are paroxytones (casa, nome, gato). The accent flags "no, the stress is on this final vowel." An oxytone ending in -i, -u, -l, -r, -z is the expected case (those endings naturally pull stress to the end), so no accent is needed: aqui, urubu, animal, amor, rapaz are all final-stressed and all unaccented.

Rule 3: Paroxytones — accented when they end the 'unusual' way

Here is the mirror image. Paroxytones are the default, so they are accented only when they end in a way a paroxytone normally would not — the endings that "naturally" signal final stress. You write the accent to say "no, despite this ending, the stress is one syllable back." Paroxytones get an accent when they end in:

The deep symmetry: the endings that accent an oxytone (-a, -e, -o, -em) are almost the opposite of the endings that accent a paroxytone (-l, -r, -i, -u, -ã, etc.). That is not a coincidence — in each case the accent flags the less expected stress for that ending.

Rule 4: Hiatus — stressed 'i' or 'u' alone after a vowel

When a stressed i or u forms its own syllable right after another vowel (a hiatus, not a diphthong), it takes an acute accent:

Two refinements worth knowing. First, after the 2009 reform the hiatus i/u is no longer accented when it comes after a diphthong in a paroxytone: old feiúra, baiúca became feiura, baiuca. Second, the accent is dropped if the i/u is followed by nh: rainha, moinho, campainha take no accent even though stress falls there.

What the 2009 reform removed

Older books and older Brazilians still write some of these the old way. The reform deleted these accents:

• Acute on the diphthongs 'ei' and 'oi' in paroxytones: old idéia, geléia, jibóia, heróico, paranóico → ideia, geleia, jiboia, heroico, paranoico.
• Circumflex on double-o (-oo): old vôo, enjôo, abençôo → voo, enjoo, abençoo.
• Circumflex on the third-person plural -eem: old crêem, lêem, vêem, dêem → creem, leem, veem, deem.
• The differential accent on 'para': old verb pára (he/she stops) → para, now spelled like the preposition. (A handful of differential accents survive: pôr the verb vs. por the preposition; pôde past vs. pode present.)

Why this is easier than it looks

English speakers expect accent placement to be irregular and lexical, the way English stress is ("PHOto-graph" vs. "phoTOGraphy" with nothing written to warn you). Portuguese is the reverse: stress is predictable from the ending, and the written accent simply marks the cases where the prediction fails. So you are not memorizing thousands of accented words — you are memorizing three rules and a default, then applying them.

Common Mistakes

Key takeaways

• The accent marks the exception to predictable default stress (paroxytone).
• Proparoxytones: ALWAYS accented (médico, rápido, sábado).
• Oxytones: accented when ending in -a(s), -e(s), -o(s), -em, -ens (sofá, café, avô, também).
• Paroxytones: accented when ending in the "unusual" way — -l, -r, -x, -n, -i(s), -u(s), -um(s), -ã(s), -ão(s), oral diphthong (fácil, açúcar, táxi, ímã, água).
• Hiatus: stressed lone i/u after a vowel takes an acute (saída, país) — but not after a diphthong or before nh.
• The 2009 reform removed idéia → ideia, vôo → voo, crêem → creem, and pára → para.