When a word refers to "an amount of money", that word is often countable.

Fro example,

debt: [countable] a sum of money that somebody owes

rent: [uncountable, countable] an amount of money that you regularly pay so that you can use a house, room, etc.

investment: [countable, uncountable] the money that you invest, or the thing that you invest in

loan: [countable] an amount of money that you borrow from a bank etc

all these words can be said in the form of "a Noun + of + $$$".

For example,

I have a debt of 200 dollars

I pay a rent of 1000 dollars a month

I have an investment of 2 million dollars in stock

I took out a loan of £60,000

Now, "interest" also means "the money..." but it is uncountable

interest 4 [uncountable]

a) the extra money that you must pay back when you borrow money interest on

The interest on the loan is 16% per year.

How much are the monthly interest payments?

b) money paid to you by a bank or financial institution when you keep money in an account there

an account that pays higher interest

The more you save, the more interest you’ll earn.

My question is:

Why is "interest" just uncountable and not countable?

Can I say "I earned an interest of 5000 dollars from my savings account"?

  • 1
    Please clarify what you're looking for. Are you looking for some rule of English to explain it? Or a logic-based reason? Or do you want a historical reason?
    – gotube
    Commented Jun 6, 2023 at 7:25
  • 1
    There are not usually many good answers to "why" questions about English. The best we can say is that general concepts or phenomena are usually uncountable.
    – stangdon
    Commented Jun 6, 2023 at 11:29
  • 1
    The etymology of "interest" is interesting: in English it originally meant a legal claim or right, from a French word for damage, loss, or harm, and came to mean compensation for default on a debt, and later the modern sense of a regular payment for a loan. See also David Graeber's Debt for much more. But that doesn't explain why it's uncountable.
    – Stuart F
    Commented Jun 6, 2023 at 13:04
  • If you want to sound like you don't know English, by all means: a Noun + of + $$$". No, interest does not mean money; interest is a percentage of some amount of money. And, fyi, we use: a $200 debt, a $5,000 loan, we don't use the word of for these things. I pay $1,000 dollars in rent per month. When are you going to close out all your questions?
    – Lambie
    Commented Jun 6, 2023 at 15:26
  • @Lambie, most dictionaries have examples such as "a debt of $$$", so that way of saying is not wrong
    – Tom
    Commented Jun 7, 2023 at 1:13

1 Answer 1


No, you can not say "I earned an interest of 5000 dollars from my savings account". Uncountable nouns can sometimes be preceded by indefinite articles, but in this case doing so would not make sense. A correct, common way of expressing this idea is:

I earned 5000 dollars in interest from my savings account.

I have no idea why "interest" (when it has this meaning) is uncountable. I think that the reasons for why many words are countable or uncountable have been lost to time.


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