Comparatives and superlatives rules: one syllable adjectives add -er/-est (faster, the fastest), one syllable ending in -e add -r/-st (nicer, the nicest), one syllable CVC double the consonant (bigger, the biggest), two syllables ending in -y change to -ier/-iest (happier, the happiest), two or more syllables use more/the most (more famous, the most famous), and common exceptions like good/better/the best.

How to form

Adjective typeComparativeSuperlativeExamples
Short (1 syllable) adj + -er the + adj + -est tall → tallerthe tallest
Short ending -e adj + -r the + adj + -st large → largerthe largest
Short CVC (consonant-vowel-consonant) double consonant + -er double consonant + -est big → biggerthe biggest
hot → hotterthe hottest
Short ending -y -y → -ier -y → -iest happy → happierthe happiest
Long (2+ syllables) more + adj the most + adj interesting → more interestingthe most interesting

Irregular forms

AdjectiveComparativeSuperlative
goodbetterthe best
badworsethe worst
farfurther / fartherthe furthest / farthest
littlelessthe least
much / manymorethe most

When Not to Use Comparative or Superlative Forms

Some adjectives already describe an absolute, all-or-nothing quality — something either is that way completely, or it isn't. These are called absolute adjectives, and they normally don't take -er/-est or more/most, because you can't have "more" of something that's already total or complete.

✗ "This is more perfect than that one." → ✓ "This one is perfect."
✗ "That's the most impossible task I've ever seen." → ✓ "That's an impossible task."

Some common absolute adjectives — this is only a partial list, English has many more absolute adjectives.
absoluteadequatealiveamazedawfulcertaincompletecorrectdeaddefectivedefinitedevoidemptyentireessentialexcellentfalsefascinatingfatalfictionalfinalfirstflawlessfreefullguiltyhopelesshugeidealimaginaryimpossibleinevitableinferiorinfiniteinvisibleirrevocableknownmainmanifestmiddleminormortalnecessaryonlyperfectpossibleprincipalsaturatedsingularstationarysuperbsuperiorterribleterrifiedtrueunavoidableuniformuniqueuniversalunknownvoidwhole

Exercises

EXERCISE:

Exercise 1 — Multiple Choice

Choose the correct form.

1. My bag is ___ than yours.

2. She is ___ student in the school.

3. This film is ___ I expected.

4. Today is ___ day of the year!