When we talk about two things, we can "compare" them. We can see if they are the same or different. Perhaps they are the same in some ways and different in other ways. We can use comparative adjectives to describe the differences.
Formation of Comparative Adjectives
There are two ways to make or to "form" a comparative adjective:
short adjectives: add "-er"
long adjectives: use "more"
Short adjectives: add -er
2-syllable adjectives ending in -y
RULE: add "-er"
old → older
Variation: if the adjective ends in -e, just add -r
late → later
Variation: if the adjective ends in consonant, vowel, consonant, double the last consonant
big → bigger
Variation: if the adjective ends in -y, change the y to i
happy → happier
Long adjectives: use more
2-syllable adjectives not ending in -y
all adjectives of 3 or more syllables
RULE: use "more"
modern → more modernexpensive → more expensive
With some 2-syllable adjectives, we can use "-er" OR "more":
quiet → quieter/more quietclever → cleverer/more clevernarrow → narrower/more narrowsimple → simpler/more simple
Exception: The following adjectives have irregular forms:
good → betterwell (healthy) → betterbad → worsefar → farther/further
Use of Comparative Adjectives
We use comparative adjectives when talking about 2 things (not 3 or 10 or 1,000,000 things, only 2 things).
Often, the comparative adjective is followed by "than".
Look at these examples:
John is 1m80. He is tall. But Chris is 1m85. He is taller than John.
America is big. But Russia is bigger.
I want to have a more powerful computer.
Is French more difficult than English?
If we talk about the two planets Earth and Mars, we can compare them as shown in the table below:
Mars is smaller than Earth.
Distance from Sun (million km)
Mars is more distant from the Sun.
Length of day (hours)
A day on Mars is slightly longer than a day on Earth.
Mars has more moons than Earth.
Surface temperature (degrees Celcius)
Mars is colder than Earth.