Amount, quantity or number?

What is the difference between 'amount of', 'quantity of' and 'number of'?
amount quantity number

Amount of 

An mount of something is  how much there is.  Amount of is used especially for something that cannot be counted or measuredIt is followed by a single noun. For example we cannot say an amount of people/shops/problems because these nouns are countable. 
  • A huge amount of information can be stored in a computer's memory. 
  • The company spent a large amount of money on advertising. 
  • They put a considerable amount of effort and time into this project. 

Quantity of  

A quantity is an amount of something that can be counted or measured.  A quantity of can be followed by a single noun or a plural noun. It is used with inanimate objects. 
  • The police found a small quantity of drugs in his apartment.  
  • They consumed a large quantity of alcohol at the party. 
  • Our country is exporting sufficient quantities of wheat. 


Be careful not to confuse quantity with quality [=how good or bad something is]. 
  • It's not the quantity, but the quality that matters. 
  • The quantity and quality of raw materials were controlled. 

Number of 

We use number of to indicate a quantity of people or things. Number of is used with plural nouns. 
After the number of we use a single verb. 
  • A large number of people attended the march. 
  • The number of people living in extreme poverty has increased substantially. 
  • A number of students have volunteered to help children. 


a huge/large/significant/vast amount of something 
a limited/small/tiny amount of something 
large/small/tiny quantity of something 
enormous/vast/huge quantities of something 
a large/small number of someone/something