The plural

If a word ends in a vowel (a, e, i, o, u), you simply add -s:

• la casa → las casas (the houses)
• el libro → los libros (the books)
• el coche → los coches (the cars)

Remember that the article also becomes plural: el/la → los/las.

If a word ends in a consonant (except -z, see next section), you add -es:

• el profesor → los profesores (the teachers)
• la ciudad → las ciudades (the cities)
• el hotel → los hoteles (the hotels)

Words that already end in -s and are unstressed on the last syllable don't change: el lunes → los lunes (Mondays), la crisis → las crisis.

If a word ends in -z, the z changes to a c before you add -es. This is a spelling rule, not a sound rule:

• el lápiz (the pencil) → los lápices
• la vez (the time/occasion) → las veces
• la luz (the light) → las luces

Remember: z + es doesn't exist in Spanish — it's always ces.

Because the plural adds a syllable, a written accent can disappear or appear, following the stress rules:

• la canción → las canciones: in the singular it ends in -n, so an accent was needed (stress on the last syllable). In the plural it ends in -s and the stress naturally falls on the second-to-last syllable (can-CIO-nes) — no accent needed anymore.
• el joven → los jóvenes: in the singular it ends in -n, stress naturally falls on the second-to-last syllable (JO-ven) — no accent needed. In the plural it ends in -s, but the stress stays on the same syllable (JÓ-ve-nes), which now breaks the rule — so it needs an accent.
• el examen → los exámenes: same pattern as joven.