Fractions

How to write fractions in Spanish

Things to know about Spanish fractions

Spanish fractions are similar to English fractions: we read the numerator as a cardinal number and the denominator as an ordinal number. The denominator is plural if the numerator is higher than 1.

Examples:

1/4 → un cuarto

3/4 → tres cuartos

Exceptions

mitad or medio (½)

The word medio is used in the same way as an adjective. It agrees with the gender and number of the noun it describes.

Examples:

medio litro de aguahalf litre of water

media docena de huevoshalf dozen eggs

The word mitad is usually followed by the preposition de + noun.

Example:

la mitad de un préstamothe half of the loan

mitad de huevos (informal: it goes without saying that it’s a dozen)

Denominators from 3 to 10

Fractions whose denominators include the numbers 3 to 10 are expressed as ordinal numbers. If the number is more than 1, the denominator is plural.

Examples:

1/3 → un tercio

4/6 → cuatro sextos

Denominators from 11

From the number 11 denominators are read as cardinal numbers with the ending –avo(s).

Example:

1/11 → un onceavo

If the denominator is a cardinal number made up of two or more words, we write them as one word. The preposition y becomes an i. In the event that two vowels appear one after another, we only write one.

Examples:

9/99 → nueve noventainueveavos

1/30 → un treintavo (not: un treintaavo)

5/108 → cinco cientochoavos (not: cinco cientoochovaos)

For multiples of ten in the tens (20, 30, 40, …), we can also use ordinal numbers.

Example:

1/40 → un cuadragésimo o un cuarentavo

However, we don’t typically use the –avo ending as an adjective.

Examples:

una vigésima parte de la población (common)a twentieth of the population

una veinteava parte de la población (less common)

For multiples of ten in the hundreds, thousands, hundred thousands etc. we always use ordinal numbers.

Example:

1/20,000 → un veintemilésimo