A comparative adjective compares two things: one is bigger, faster or more useful than the other. A superlative picks one out of a group of three or more: it is the biggest, the fastest or the most useful of them all. That is the whole idea. The grammar that trips learners up is not the meaning; it is knowing when to bolt -er onto the end of a word and when to reach for more instead. This guide sorts that out.

Comparative or superlative?

The choice comes down to how many things you are comparing.

• Use a comparative to compare two things. My brother is taller than me. Two people, one comparison.
• Use a superlative to pick one out of three or more. My brother is the tallest in the family. One winner, a whole group behind them.

If there are only two things, a superlative is wrong: the tallest of the two should be the taller of the two. Get the count right and the rest follows.

The core rules by syllable count

English decides between -er/-est and more/most mostly by counting syllables. There are four rules and one master table that holds them all.

One syllable: add -er and -est.

tall becomes taller and tallest. This covers the everyday words: fast, old, small, cheap, short.

One syllable ending consonant-vowel-consonant: double the last consonant.

When a short word ends in a single consonant, a single vowel and a single consonant, you double that final consonant before adding the ending. big becomes bigger and biggest; hot becomes hotter and hottest. The double letter keeps the vowel short.

Ending in -y: change the y to i.

Two-syllable adjectives that end in -y swap the y for i and add -er or -est. happy becomes happier and happiest; easy becomes easier and easiest. This rule beats the syllable count, so even though happy has two syllables, it does not take more.

Two or more syllables: use more and most.

For longer adjectives, leave the word alone and put more or most in front. careful becomes more careful and most careful; useful becomes more useful and most useful. You never add -er to these, and you never use both more and -er together.

The common irregulars

A handful of the most-used adjectives ignore the rules entirely. There is no logic to memorise here; you simply learn them, and because they are so common you will use them daily until they stick.

Better and best are the ones you will meet first: her English is better than mine, this is the best coffee in town. For far, both spellings are correct; British English tends to prefer further for distance and figurative use alike, while farther is more common for physical distance in American English. Either is safe.

The patterns that carry the words

Knowing how to build the word is half the job. The other half is the small set of words that surround it.

than after a comparative. A comparative almost always leads to than. She is taller than me. This bag is cheaper than that one. Forgetting than is one of the most common slips.

the before a superlative. A superlative almost always takes the in front. He is the tallest. This is the hottest day of the year. The superlative points to one specific thing, and the is how English marks something specific.

as ... as for equality. When two things are equal, you do not need a comparative at all. Wrap the plain adjective in as ... as: she is as tall as her brother, this book is as good as the film. To say they are not equal, add not: it is not as hot as yesterday.

less and the least for the other direction. More and -er push upward; less and the least pull the other way. This route is less busy than that one. It is the least expensive option on the menu. These work with longer adjectives; for short ones, most speakers just use the opposite word (smaller rather than less big).

Common mistakes

Ranked by how often learners actually make them.

1. Double comparatives. Using more and -er together, as in more bigger or more taller, is wrong. Pick one: bigger, not more bigger. The same goes for superlatives: the most tallest should be the tallest.
2. more better and more worse. Because better and worse are already comparatives, they never take more. My English is more better should be my English is better.
3. Forgetting than. She is taller me is missing its comparison word: she is taller than me. If there is a comparative, look for the than.
4. Using a superlative for two things. She is the tallest of the two sisters should be she is the taller of the two sisters. Three or more before you reach for a superlative.
5. than and then mixed up. He is older then me should be older than me. Than compares; then tells the time. They are different words that happen to sound alike.

Practice

Choose or complete the correct form. Answers are below.

1. A plane is ___ (fast) than a train.
2. This is the ___ (hot) day of the summer.
3. My new phone is ___ (expensive) than my old one.
4. She is a ___ (good) singer than her sister.
5. Today is not ___ cold ___ yesterday.

Answers: 1. faster (one syllable, add -er, plus than) 2. hottest (double the consonant, superlative with the) 3. more expensive (three syllables, use more plus than) 4. better (good is irregular, never gooder) 5. as ... as (not as cold as for unequal things)