The difference between number and amount

One thing that both frustrates and delights me about the English language is how certain word rules weave together and rely upon the same basic foundation. As with my previous post on the difference between less and fewer, which both depend upon their relation to either mass or count nouns, so too is the case here.

If you’re visiting this site for the first time (welcome!), and have no idea what a mass noun is, let alone its difference to a count noun, allow me to briefly go over the rules below.

A count noun is something you can (of course) count, such as plants, birds, tiles, tyres and thousands of other things. Equally important, though, is that you can identify a single one of those things—you can easily identify a single blanket, for instance. On the other hand, a mass noun is something that cannot be counted, such as gas, knowledge, furniture, joy, fruit and heat. You cannot count a single one of these—ie, there is no such thing as a single joy or a single heat. In order to count these nouns, you would have to introduce some kind of measurement; for instance, a cannister of gas or ounce of knowledge.

So while the words ‘number’ and ‘amount’ both refer to something’s size or value, the words must play by the rules of mass and count nouns. Firstly, the word ‘number’ must be used with referring to a count noun, due to the fact that—as the word ‘number’ itself hints—count nouns can be singularly identified. For instance:

The number of people at the bus stop was more than usual.
It was clear there was some kind of infestation, judging by the number of mouse holes.
The company is looking to close down a number of its stores.

In the above examples, people, mouse holes and stores can all be counted individually; however, when identifying the value of a mass noun, ‘amount’ must be used.

The amount of rice you gave me wasn’t enough.
A decent amount of exercise is good for the brain and body.
The amount of heat radiating off the car bonnet could fry an egg in seconds.

This is another of those common mistakes that people often commit in spoken language. Once you master this rule, you’ll notice just how many of your friends, family and colleagues slip up, even in their writing. Just like with learning ‘less vs fewer’ and ‘mass vs count nouns’, however, the ‘number vs amount’ rule will stick like glue once you’ve got it. Promise!