This document from the English Department of Mario Quirós Technical High-School provides instructions on forming comparative adjectives in English. It explains that one-syllable adjectives typically take -er in the comparative, two-syllable adjectives typically take "more" in the comparative, and adjectives with three or more syllables always take "more." It also notes exceptions for irregular adjectives like "good" and "bad." Examples are provided to illustrate the rules for forming comparatives of different types of adjectives.

1. Mario Quirós Technical High-School
English Department
Level: 8th graders
Professor: Ariel Martínez S.
Comparative form of adjectives
1. One-syllable adjectives.
Form the comparative of a one-syllable adjective by adding -ER
One-Syllable Adjective
Comparative Form
tall
taller
old
older
long
longer

Mary is taller than Max.

Max is older than John.

My hair is longer than your hair.
If the one-syllable adjective ends with an E… just add –r for the comparative
form
Examples:
RudE
RUDer
LargE
LARGer
WisE
WISer

2. If the one-syllable adjective ends with a single consonant with a vowel before it,
double the consonant and add –er for the comparative form; and double the consonant.
One-Syllable Adjective Ending
with a Single Consonant with a
Single Vowel before It
Comparative Form
big
bigger
thin
thinner
fat
fatter

My dog is bigger than your dog.

Max is thinner than John.

My mother is fatter than your mother.
2. Two-syllable adjectives.
With most two-syllable adjectives, you form the comparative with more and the
superlative with most.
Two-Syllable
Comparative Form
Adjective
peaceful
more peaceful
pleasant
more pleasant
careful
more careful

This morning is more peaceful than yesterday morning.

Max is more careful than Mike.

3. If the two-syllable adjective ends with a –Y, add –er for the comparative form.
Two-Syllable
Adjective Ending
Comparative Form
with -y
happy
happier
angry
angrier
busy
busier

John is happier today than he was yesterday.

Max is angrier than Mary.

Mary is busier than Max.
Two-syllable adjectives ending in –er, -le, or –ow take –er and –est to form the
comparative and superlative forms.
Two-Syllable Adjective
Comparative Form
Superlative Form
narrow
narrower
narrowest
gentle
gentler
gentlest
Ending with -er, -le, or -ow

The roads in this town are narrower than the roads in the city.

4. 
This road is the narrowest of all the roads in California.

Big dogs are gentler than small dogs.

Of all the dogs in the world, English Mastiffs are the gentlest.
3. Two or more syllable adjectives.
For adjectives with three syllables or more, you form the comparative with more.
Adjective with Three
Comparative Form
or More Syllables
generous
more generous
important
more important
intelligent
more intelligent

John is more generous than Jack.

Health is more important than money.

Women are more intelligent than men.

5. Be careful with exceptions
Irregular adjectives.
Irregular Adjective
Comparative Form
good
better
bad
worse
far
farther
little
less

Italian food is better than American food.

My mother's cooking is worse than your mother's cooking.
Two-syllable adjectives that follow two rules. These adjectives can be used with
–er.
Two-Syllable
Adjective
Comparative Form
clever
cleverer
clever
more clever
gentle
gentler
gentle
more gentle
friendly
friendlier
friendly
more friendly
quiet
quieter
quiet
more quiet
simple
simpler
simple
more simple

6. 



Big dogs are gentler than small dogs.
Of all the dogs in the world, English Mastiffs are the gentlest.
Big dogs are more gentle than small dogs.
Of all the dogs in the world, English Mastiffs are the most gentle.
Adapted from: http://www.eflnet.com/tutorials/adjcompsup.php