Spanish flag

Irregular comparatives: 'mejor', 'peor', 'mayor', and 'menor'

In English, you would never say "more better" or "more worse". Spanish has a very similar rule. While most Spanish adjectives and adverbs form comparisons by simply adding más (more), a few very common concepts have special, irregular forms that do the job all by themselves.

The words mejor, peor, mayor, and menor already contain the meaning of "more". Because they do the heavy lifting for you, the most important rule is to never put más in front of them. Saying más mejor is a very common trap for learners, but it sounds just as repetitive as "more better".

Word list
mejorA1 better never más mejor - adjective, replaces más bueno mayorA2 older never más mayor - used for age mayorA2 bigger never más mayor - used for scale or importance mejorA2 better never más mejor - adverb, stays singular menorA2 younger never más menor - used for age menorA2 smaller never más menor - used for scale or degree peorA2 worse never más peor - adjective, replaces más malo peorA2 worse never más peor - adverb, stays singular
Better and Worse

When you want to say that something is better or worse, you will use mejor and peor. These words completely replace the need to say más bueno (more good) or más malo (more bad).

They work as both adjectives (describing a noun) and adverbs (describing how an action is performed). You can use them to compare two things, or just to state that something is an improvement or a downgrade.

Este coche es mejor.
(This car is better.)
Hoy los sistemas funcionan peor.
(Today the systems work worse.)
Older and Younger

In Spanish, age is treated as a degree of greatness. Instead of saying someone is "more old", you use mayor (older). For "more young", you use menor (younger). You will hear these words constantly when people talk about their families and siblings.

Mi hermano mayor tiene veinte años.
(My older brother is twenty years old.)
Ella es mi hermana menor.
(She is my younger sister.)

These two words can also mean "greater" or "lesser" when talking about the importance or scale of a problem. However, there is a catch when talking about physical size. If you are simply describing how physically big or small an object is, it is completely normal and correct to use más grande (bigger) and más pequeño (smaller).

El riesgo es mayor de lo que pensábamos.
(The risk is larger than we thought.)
Watch out for plurals

When mejor, peor, mayor, and menor act as adjectives, they must agree with the noun they describe. Since they end in a consonant, you make them plural by adding -es.

Estos libros son mejores que aquellos.
(These books are better than those ones.)

However, when mejor and peor are used as adverbs to describe an action, they do not change. Adverbs never have a plural form, even if multiple people are doing the action.

Ellas cantan mejor.
(They sing better.)
Summary

The words mejor, peor, mayor, and menor have the idea of "more" built right into them. Never add más in front of them, remember to make them plural when they describe plural nouns, and use them confidently to compare things like a native speaker.