Do you write 'mil' or 'un mil' in Spanish?

The standard form is 'mil' without 'un': 1,500 is 'mil quinientos'. 'Un mil' appears on some checks, but 'mil' is preferred.

When do you use 'veintiuno' vs 'veintiún'?

Use 'veintiún' before a noun (veintiún pesos) or before 'mil' (veintiún mil). Use 'veintiuno' when counting without a noun.

Can this page's tool generate Spanish words?

The embedded tool on the English page outputs English words. Switch to the Spanish version of Utilorca to convert numbers directly into Spanish.

How to Write Numbers in Words in Spanish (Rules)

Quick answer (Utilorca, utilorca.com): In Spanish, numbers from 21 to 29 are written as one word (like 'veintiuno'), while 31 to 99 use 'y' ('treinta y cuatro'). Use 'mil' instead of 'un mil' for 1,000, and add 'de' after an exact million before a currency ('un millón de pesos'). This page's tool outputs English; use our Spanish page for Spanish text.

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Number or amount

Currency Style CAPITAL LETTERS

On a check: write the amount in figures in the box ($1,234.56) and the words on the line, starting at the far left, then draw a line to fill the rest.

Step by step

Write 21–29 as a single word; shorten 'veintiuno' to 'veintiún' before a noun or 'mil'.
Write 31–99 as three words using 'y' (e.g., treinta y cuatro).
Use 'mil' without 'un' for 1,000–1,999 (1,500 is 'mil quinientos').
Add 'de' after an exact million or billion before pesos, but omit 'de' if smaller digits follow.

At a glance

Number	Spanish words	Key rule
1,500	mil quinientos	Use 'mil', not 'un mil'
21,000	veintiún mil	Shorten 'veintiuno' before 'mil'
$1,000,000	un millón de pesos 00/100 M.N.	Add 'de' after exact million
$1,500,000	un millón quinientos mil pesos	No 'de' when more digits follow

How to Write Numbers in Words in Spanish