Cardinales 0-30

The first thirty numbers are the most-used numbers in any language — for ages, prices, times, dates, phone digits, lottery picks and a thousand other everyday tasks. Spanish numbers 0–30 are mostly regular, but they contain three traps worth knowing about from the start: a small set of irregular teens (11–15), a fused one-word form for 16–29 that takes accents on certain numbers, and gender agreement that affects uno and veintiuno before nouns. This page covers all three and gives you the full list with pronunciation hints.

The full list, 0–30

The irregular teens: 11–15

The numbers from 11 to 15 are irregular — they don't fit the diez y… pattern that 16–19 follow. They descend from Latin compounds that were already fused in the parent language (Latin undecim, duodecim, tredecim, quattuordecim, quindecim).

There is no shortcut here — you have to memorise the five forms. The good news is that they are extremely high-frequency, and you will internalise them within your first week of real Spanish exposure.

The dieci- fusions: 16–19

From 16 onwards, Spanish builds compound numbers by fusing the ten and the unit into a single word. The connector y ("and") softens to i and the whole thing is written together.

• dieciséis = diez y seis, fused. Note the obligatory accent on the é.
• diecisiete = diez y siete, fused.
• dieciocho = diez y ocho, fused — the z drops and the vowels collide directly.
• diecinueve = diez y nueve, fused.

Spelling them as three words (diez y seis) is now an archaic style — you'll see it occasionally in old texts and very formal legal writing, but in everyday Spanish always write the fused form.

The veinti- fusions: 21–29

The same fusion applies to 21–29: veinte + unit becomes one word, with the -e of veinte softening to -i before the unit. Like the teens, several of these carry obligatory accents.

The accent pattern is mechanical: any time the fused word ends in -s and has its stress on the last syllable, it gets an accent (-dós, -trés, -séis). The others don't.

Note that 21–29 are written as one word, but 31 and higher are written as three words with y (treinta y uno, cuarenta y dos). This split is one of the more arbitrary features of the system; it's a frozen historical accident. See the cardinals 31–100 page for the longer pattern.

Gender and apocope: uno, un, una — and veintiún

The number one has three forms in Spanish, depending on what follows it.

This is the same shape as the indefinite article (also un, una, uno), and the number and the article share the same morphology — they are historically the same word.

Veintiuno also apocopates

The same logic applies to twenty-one: veintiuno → veintiún before a masculine singular noun, veintiuna before a feminine singular noun. The apocope before masculine nouns is obligatory and the resulting form carries an accent (because veintiún is aguda and ends in -n).

Reading prices, ages, phone numbers

Spanish reads numbers in chunks in the same way English does for everyday quantities.

Phone numbers in Spain are nine digits, typically read as two-three-two-two (XX XXX XX XX) or three-three-three (XXX XXX XXX) in chunks, not digit by digit.

Common Mistakes

Key takeaways

• The teens 11–15 (once, doce, trece, catorce, quince) are irregular — pure memorisation.
• 16–19 use a fused dieci- form; dieciséis takes an obligatory accent.
• 21–29 use a fused veinti- form; veintidós, veintitrés, veintiséis take obligatory accents.
• Uno → un before masculine singular nouns, una before feminine. Same for veintiuno → veintiún / veintiuna.
• Peninsular Spanish pronounces c (before e/i) and z as /θ/ — so cinco, once, diez all contain the th sound.
• The number 30 is treinta and starts the new pattern treinta y uno, treinta y dos… — covered on the cardinals 31–100 page.