Accent Marks: Complete Rules

The Spanish tilde (the written accent mark — á, é, í, ó, ú) looks decorative, but it's highly informative. It tells you exactly where the stress of a word falls, and in some cases it distinguishes two otherwise identical words. This master reference walks through every situation where a Spanish word gets (or loses) a tilde.

Two concepts underpin the whole system:

1. Every multi-syllable Spanish word has one stressed syllable. If you can predict where the stress falls from the spelling, you don't need a mark. If you can't, you write a tilde.
2. The tilde is always a diagonal line going from lower-left to upper-right (á). It's not the wavy mark on ñ — that's called a virgulilla and is part of the letter, not an accent.

Everything else is built from these two ideas.

1. The Three Basic Stress Rules

Start here. These three rules cover at least 95% of Spanish words.

The principle: if the word follows the default, no tilde. If it breaks the default, write a tilde on the stressed vowel.

Examples of "follows the default, no tilde"

Examples of "breaks the default, needs a tilde"

See stress rules and written accent marks.

2. The Diphthong-Breaking Tilde (Hiatus Marker)

Spanish groups certain vowel combinations into a single syllable called a diphthong: i or u next to a, e, or o (for example ai, au, ie, io, ua, ue). These count as one syllable.

But if the stress falls on the weak vowel (i or u), the pair breaks apart into two separate syllables. This is called hiatus, and Spanish marks it with a tilde on the weak vowel — regardless of the stress rules above.

This tilde overrides the basic stress rules. País ends in s, so by default it would be llana (pa-is as one syllable). The tilde tells you: no, it's two syllables, with stress on the í. See diphthongs and hiatus.

3. Interrogative and Exclamatory Accents

Question and exclamation words always wear a tilde, even though their stress would otherwise be predictable without one. The purpose here isn't phonetic — it's to distinguish them from their non-interrogative homographs.

Note that the tilde appears even in indirect questions (no actual question mark): Dime qué pasó, No sé cuándo llegaron. If the word is asking something — even implicitly — it takes a tilde.

4. Diacritical Accents — Small Words That Change Meaning

A handful of one-syllable words never "need" a tilde by the basic stress rules, since all monosyllables are unambiguous. But Spanish marks some of them to distinguish pairs of words spelled identically.

See diacritical accents.

5. Demonstratives — No Longer Accented

Older Spanish textbooks insist that éste, ése, aquél (as pronouns) must wear a tilde. Since the 2010 RAE reform, that tilde is no longer required, even as a pronoun — este, ese, aquel are correct in all uses. You'll still see the tilde in older texts; it's not wrong, just outdated.

The neuter forms esto, eso, aquello never wore a tilde in the first place (there's nothing to disambiguate them with).

6. Verb Forms With Attached Pronouns

When you attach one or more pronouns to a verb (infinitive, gerund, or affirmative command), the word usually grows an extra syllable or two, and the stress syllable moves further from the end. In many cases this pushes the word into esdrújula or sobreesdrújula territory, and the tilde becomes obligatory.

The underlying rule never changes: if the spoken stress is now on the third-to-last (or earlier) syllable, mark it. Once you internalize the esdrújula rule, these verb-plus-pronoun cases feel automatic.

See imperative accent marks.

7. When an Accent Disappears in the Plural

Some nouns and adjectives lose their tilde when pluralized, because adding a syllable makes the word fit the default rule.

Notice how joven gains an accent (jóvenes) while francés loses one (franceses) when they pluralize. Same rule, opposite directions.

8. Common Misplaced Accents

These are the classic errors even intermediate learners keep making.

9. Stress Rules vs. Diacritical Accent: A Mental Separator

Learners often mix up two totally different functions of the tilde:

• Stress rule tildes mark the position of spoken stress. They are phonetic.
• Diacritical tildes distinguish homograph pairs. They are orthographic only and don't change pronunciation.

Both use the exact same mark, but they answer different questions. When you see a tilde, it's doing one or the other (occasionally both at once, as in cómo — the tilde is diacritical since the natural stress is already on co-mo, but it's still marking the difference from como).

10. Complete Summary Table

11. Practice Examples

Summary

• Spanish marks stress only when the default rule (llana for n/s/vowel endings, aguda for other consonants) is broken.
• Esdrújulas (stress three or more back) always take a tilde.
• A tilde on a weak vowel (i, u) breaks a diphthong into two syllables: día, país, baúl, frío.
• Interrogative and exclamatory words always wear a tilde, even in indirect questions.
• Diacritical accents distinguish homograph pairs like tú/tu, él/el, sí/si, mí/mi, té/te, sé/se, dé/de, más/mas.
• When pronouns attach to a verb, check whether the resulting word is now esdrújula or sobreesdrújula and mark accordingly.
• Plural forms can gain (joven → jóvenes) or lose (francés → franceses) a tilde as the stress pattern changes.
• The 2010 RAE reform removed the tilde from sólo (as "only") and from pronoun éste/ése/aquél.

Once these nine points are in your head, the tilde stops being a mystery and becomes a useful signal — each mark is telling you something specific about the word you're reading.