Short adverbs that do not end in -ly add”-er” to their comparative forms and “-est” to form the superlative. Remove the “e” before adding the ending if the adverb ends with an “e”.
Adverbs ending in -ly use “more” to form the comparative, and “most” to form the superlative.
IRREGULAR COMPARATIVES AND SUPERLATIVES
These comparatives and superlatives do not conform to the regular rules of their forms.
Comparative and Superlative Adverbs