Comparative adjectives like taller or more expensive tell you two things are different. But what if they're the same? English has a separate structure for that: as … as.
The one rule to remember. To say two things are equal, sandwich the plain adjective or adverb between two as: as + adjective/adverb + as. No -er, no more — just the plain word. ✅ as tall as, never ❌ as taller as.
Equal comparisons: as … as
Use as + adjective + as when two things are equal in some way:
- My brother is as tall as me.
- This café is as good as the one downtown.
- Her new phone is as fast as mine.
The adjective goes in its plain, base form — never the comparative. ✅ as expensive as, never ❌ as more expensive as.
The same pattern works with adverbs, not just adjectives: She finished as quickly as she could. · He didn't drive as carefully as usual.
This lesson focuses on adjectives and adverbs. Quantities use a different pattern worth knowing about but not covered here: as much time as, as many books as.
Making it negative: not as / so … as
To say two things are not equal, add not before the first as. You can also swap that first as for so — both are correct, but not so … as sounds a little more old-fashioned or formal:
- This test wasn't as hard as the last one.
- He isn't as busy as he used to be.
- The film wasn't so exciting as I expected. (a bit more formal than as … as)
Notice what this negative form actually means: not as hard as just means the first thing is less hard than the second — it doesn't say how big that gap is. For that, you need the modifiers below.
Softening and strengthening the comparison
You can put a word in front of the first as to say how close the two things are to being equal:
| Modifier | Meaning | Example |
|---|---|---|
| just as | equal, with emphasis | This one is just as good as that one. |
| nearly as / almost as | very close, but slightly less | She's almost as tall as her mother. |
| not quite as | close, but a little less | The sequel isn't quite as funny as the original. |
| not nearly as | far less — a big gap | This café isn't nearly as cheap as the one near my home. |
- This laptop is just as fast as the old one — they feel equally fast.
- He isn't nearly as tired as he looks — this stresses a big gap. Plain isn't as tired as just says he's less tired; it doesn't say how big that gap is.
Measuring the gap: twice as, half as, three times as
To say exactly how many times bigger or smaller something is, put a multiple in front of as … as:
- This flat is twice as expensive as my old one. (2×)
- The queue moved half as fast as yesterday. (½×)
- Their new office is three times as big as the old one. (3×)
For clear, natural B1 English, use multiple + as + adjective + as: twice as big as. You may come across forms like three times bigger than in more advanced or technical English, but they can sound ambiguous, so this lesson sticks with the clearer as … as pattern. ✅ twice as big as, not ❌ twice bigger than at this level.
as … as vs -er / more
Both structures compare two things, but they answer different questions:
| Structure | Question it answers | Example |
|---|---|---|
| -er / more + than | Which one has more or less of the quality? | This one is bigger than that one. |
| as … as | Are they equal, or how close are they to equal? | This one is as big as that one. |
The -er / more comparatives can also be softened or strengthened to show how big the gap is (a bit bigger, much more expensive, far cheaper) — that's its own topic with its own set of modifiers, worth studying separately once as … as feels comfortable.
A note on pronouns after as. In everyday speech, an object pronoun is completely natural: as tall as me, as good as her. In more formal writing, you'll also see a subject pronoun with a verb: as tall as I am, as good as she is. Both are correct — the object-pronoun version is just more relaxed.
Common mistakes
- ❌ She is as taller as me. → ✅ She is as tall as me. (plain adjective, not comparative)
- ❌ This is as more expensive as that. → ✅ This is as expensive as that.
- ❌ It's twice bigger than the old one. → ✅ It's twice as big as the old one. (at this level, keep multiples with as … as)
- ❌ He isn't so good than her. → ✅ He isn't as good as her / ✅ He isn't so good as her. (as … as / so … as, never so … than)
- ❌ This bag is not as cheap than that one. → ✅ This bag is not as cheap as that one.
Quick check
Complete each sentence with the correct form:
- My sister is ____ (tall) ____ me. (they're exactly equal)
- This coffee isn't ____ (strong) ____ the one at home. (it's weaker)
- The new bridge is ____ (long) ____ the old one. (exactly double)
- He's ____ (fast) ____ his brother — just a tiny bit slower. (use almost)
- This flat is ____ (big) ____ my last one — a huge difference. (use not nearly)
Show answers
- as tall as 2. as strong as 3. twice as long as 4. almost as fast as 5. not nearly as big as
Key takeaways
- Equal comparisons use as + plain adjective + as — never the comparative form: ✅ as tall as, never ❌ as taller as.
- Make it negative with not as / so … as: not as hard as, not so exciting as.
- Soften or strengthen it with just as (equal), nearly / almost as (very close), not quite as (a little less), or not nearly as (a big gap).
- Measure the exact gap with a multiple: twice as, half as, three times as — clearer than putting a multiple in front of -er / more.
- as … as asks "are they equal?"; -er / more + than asks "which one has more?" — different questions, different structures.