Both words describe how much there is. The difference is whether you can count it.
- Number goes with things you can count one by one: books, pebbles, people.
- Amount goes with things you cannot count one by one: water, sand, homework, time.
Number: things you can count
Use number when the thing is plural and you could count each one.
A large number of students joined the club.
The number of pebbles on the beach is huge.
A small number of birds visited the garden.
You can say three books or forty students, so you say a number of books or students.
Amount: things you cannot count
Use amount when you measure the thing instead of counting it one by one.
There is a large amount of water in the lake.
I have a huge amount of homework.
It takes a small amount of time to tie your shoes.
You do not say three waters when you mean a whole lake, and you do not say three homeworks. So you use amount.
Easy way to tell them apart
Ask: can I put a number in front of it?
- Three books. Yes, so use number.
- Three sands. No, so use amount.
If the noun is plural (ending in -s), it is almost always number.
💡 The OddLingo Trick
Think of a pebble and sand.
You can pick up one pebble, and another, and count them: a number of pebbles. You cannot count sand grain by grain, so you say an amount of sand.
⚠️ Common mistakes
Plural things you can count? Use number.
❌ A large amount of students came.
✅ A large number of students came.
Things you cannot count? Use amount.
❌ There is a huge number of homework.
✅ There is a huge amount of homework.
Time is not counted one by one.
❌ It takes a small number of time.
✅ It takes a small amount of time.
Good to know
There is a nice link with less and fewer. Use fewer with things you can count and less with things you cannot count. Fewer books, less water. The rule is the same: can you count it?
A number of is followed by a plural verb: A number of students are late. The number of is followed by a singular verb: The number of students is growing.
💬 In a conversation
Zoe: What a huge amount of pasta!
Sam: It is. And there is a large number of pasta shapes.
Zoe: Can we count them?
Sam: Not before dinner.