Quick answer
libro → libros · ciudad → ciudades
Add -s after a vowel, -es after a consonant. Spelling and written accents then adjust around the new syllable.
The two endings
| Ends in | Add | Example |
|---|---|---|
| vowel | -s | casa → casas |
| consonant | -es | ciudad → ciudades |
| -z | -ces | lápiz → lápices |
| stressed -í / -ú | -es | israelí → israelíes |
| unstressed -s | no change | el lunes → los lunes |
With the no-change group, only the article tells you the number: la crisis / las crisis.
Accents that appear or vanish
The plural adds a syllable, so a written accent that was only there to mark stress may no longer be needed — or may suddenly be needed.
A masculine plural can cover both
A mixed group takes the masculine plural, and some family words work this way by default.
Memory trick
Everything in the noun phrase moves together: article, noun and adjective all take the plural mark, not just the noun.
Typical mistakes
Tengo dos lápizes.
Tengo dos lápices.
A final z becomes c before -es. The spelling follows the sound.
Los examenes son difíciles.
Los exámenes son difíciles.
The extra syllable shifts the stress pattern, so the plural needs a written accent.
Las casa blancas.
Las casas blancas.
Every word in the phrase carries the plural, including the noun itself.
Check yourself
una ciudad → dos ___