Comparative adverbs express how an action is performed in relation to another action, to another person, or to another quantity. They are used to compare degree, intensity, or frequency without changing the adverb's form for gender or number, as happens with other adverbs. They are also combined with equality, superiority, and inferiority structures that allow specifying the relationship between two terms. It also notes that they can be combined with equality, superiority, and inferiority structures that allow specifying the relationship between two terms in sentences.

The comparison of superiority and inferiority is formed with more or less in front of the adverb. The usual structure is more or less followed by the adverb, and then 'que' appears when comparing with another person or action. In this pattern, the adverb usually preserves its base form and does not agree with the subject.

IdeaIdea	EjemploExample
La superioridad adverbial se expresa con más delante del adverbio.Adverbial superiority is expressed with más in front of the adverb.	Corre más rápido que yo.He runs faster than I do.
La inferioridad adverbial se expresa con menos delante del adverbio.Adverbial inferiority is expressed with menos in front of the adverb.	Habla menos claramente que ayer.He speaks less clearly than yesterday.
El adverbio no cambia por género ni número.The adverb does not change for gender or number.	Ellas trabajan más cuidadosamente que antes.They work more carefully than before.

Adverbial equality can be expressed with tan + adverb + como, or with igual de + adjective or adverb + que. In many speakers, tan appears more naturally before adverbs, while igual de is common and very clear in equality comparisons. These constructions are used to signal that two actions have the same degree, the same speed, or the same intensity.

IdeaIdea	EjemploExample
Tan compara el grado de un adverbio con otro término.Tan expresses the degree of an adverb relative to another term.	Habla tan alto como ella.She speaks as loudly as she does.
Igual de introduce igualdad con adjetivos o adverbios.Igual de introduces equality with adjectives or adverbs.	Trabaja igual de rápido que su hermana.She works igual de fast as her sister.
Tan no cambia por género ni número.Tan does not change for gender or number.	Cantan tan bien como antes.They sing as well as before.

Tanto is used with verbs, quantities, and nouns, while tan is used with adjectives and adverbs. In negative comparisons, no tanto expresses a lower degree. This distinction is important because tanto and tan are not interchangeable, and the choice depends on the category that accompanies the comparison.

IdeaIdea	EjemploExample
Tanto acompaña verbos y cantidades.Tanto accompanies verbs and quantities.	No trabaja tanto como antes.He doesn't work as much as before.
No tanto como indica menor grado.Not as much as indicates a lower degree.	Llueve no tanto como en invierno.It doesn't rain as much as in winter.
Tan no introduce un verbo como complemento directo de comparación.Tan does not introduce a verb as a direct object of comparison.	Escribe tan rápido como responde.He writes as fast as he responds.

Some adverbs show irregular comparison and do not form the comparative with more. Well changes to better and badly changes to worse, so the comparison is expressed with these special forms. These variants are mandatory in standard usage and are essential to describe changes in quality or manner of acting.

IdeaIdea	EjemploExample
Bien forma el comparativo irregular mejor.Bien forms the irregular comparative better.	Canta mejor ahora.He sings better now.
Mal forma el comparativo irregular peor.Mal forms the irregular comparative worse.	Se siente peor hoy.He feels worse today.
Las formas irregulares sustituyen a más bien y más mal en la comparación estándar.Irregular forms replace more well and more badly in standard comparison.	Toca mejor que ayer.He plays better than yesterday.

Many adverbs ending in -mente form their comparative with more. The structure indicates that the action is performed with greater or lesser degree of care, clarity, or precision. In these comparisons, the adverb continues to function as a verbal modifier and preserves its invariable nature, as also explained in Placement of Adverbs and Modality Adverbs.

IdeaIdea	EjemploExample
Los adverbios terminados en mente comparan con más.Adverbs ending in mente compare with more.	Explica más cuidadosamente que antes.Explain more carefully than before.
La forma en mente no cambia por concordancia.The -mente form does not change for agreement.	Piensan más claramente hoy.They think more clearly today.
La comparación puede resaltar precisión o intensidad.The comparison can emphasize precision or intensity.	Escribe más rápidamente que ayer.He writes more quickly than yesterday.

The comparative adverb is typically placed after the verb, though it can be fronted or displaced for emphasis. When the comparison is long, the position of the adverb helps maintain clarity of the relation between the verb and the term being compared. The placement of the comparative follows the same general principles of adverbial distribution as in everyday use.

IdeaIdea	EjemploExample
El adverbio suele ir después del verbo.The adverb usually goes after the verb.	Actúa más naturalmente que su compañero.He acts more naturally than his partner.
El desplazamiento puede marcar énfasis.Fronting can mark emphasis.	Más suavemente habla ella en clase.She speaks more softly in class.
La posición influye en la claridad de la comparación.Position affects the clarity of the comparison.	Responde más lentamente que el resto.They answer more slowly than the rest.

Adverbial comparisons must distinguish between equality, superiority, and inferiority to avoid mixing form and meaning. In colloquial speech, more better may appear, but that form is not standard because better already carries the comparative idea. It is also worth remembering that more than can mean to a greater degree, but in some contexts it can be equivalent to more or less than, so the meaning depends on the sentence context.

IdeaIdea	EjemploExample
Más mejor no es una forma estándar.More better is not a standard form.	Habla mejor ahora.He speaks better now.
Más que puede expresar superioridad.More than can express superiority.	Corre más que yo.He runs more than I do.
Más que puede significar más bien que en ciertos contextos.More than can mean more or less than in certain contexts.	Es prudente más que valiente.He is more prudent than brave.

Adverbial comparatives allow measuring how an action occurs relative to another, whether with more and less, with tan and igual de, or with irregular forms such as better and worse. Using them correctly depends on choosing the appropriate structure, respecting the adverb's invariable nature, and placing the comparison clearly in the sentence. With these guidelines, degree, equality, and difference are expressed precisely in written and spoken Spanish.