Cuatro vs. cuarto
The Spanish words cuatro and cuarto are often confused by learners due to their similar spelling. However, they have completely different meanings and uses. Cuatro refers to a quantity, while cuarto can refer to a space, a fraction, or an order in a sequence.
Cuatro
A1The word cuatro is a cardinal number and it means four (4). It is used to count things and its form does not change.
Tengo cuatro hermanos en mi familia.
(I have four siblings in my family.)
La reunión empieza a las cuatro de la tarde.
(The meeting starts at four in the afternoon.)
Compramos una mesa con cuatro sillas.
(We bought a table with four chairs.)
El niño ya sabe contar hasta cuatro.
(The child already knows how to count to four.)
Cuarto
A1The word cuarto is very versatile. As a noun, it means room or a quarter (1/4). As an adjective, it is an ordinal number meaning fourth (4th) and must agree in gender with the noun it describes (cuarto for masculine, cuarta for feminine).
Mi cuarto tiene una ventana muy grande.
(My room has a very big window.)
Necesito un cuarto de kilo de jamón.
(I need a quarter of a kilo of ham.)
Él vive en el cuarto piso del edificio.
(He lives on the fourth floor of the building.)
Es la una y cuarto.
(It is a quarter past one.)
Esta es la cuarta vez que visito esta ciudad.
(This is the fourth time I have visited this city.)
Por favor, limpia el cuarto de baño.
(Please, clean the bathroom.)
Summary
In summary, cuatro always means the number four (4). In contrast, cuarto can mean a room (like a bedroom), a quarter (like a quarter of an hour), or the ordinal number fourth (like the fourth place). The key is to remember that cuatro is for counting, while cuarto is for describing a space, a fraction, or a position in a sequence.