“amount” vs. “number”
Use "amount" before uncountable nouns and "number" before countable nouns — the identical grammatical test used for much/many and fewer/less.
amount
"Amount" refers to a quantity of something uncountable ("a large amount of water," "the amount of effort required"). "Amount" comes from Old French "amonter," meaning to ascend or add up to a total ("mont-" relating to mountain and climbing), originally used for adding up sums of money before broadening to any uncountable quantity.
number
"Number" refers to a quantity of something countable ("a number of people," "the number of mistakes"). "Number" comes from Latin "numerus," the same root behind "numeral" and "numerous," and has always specifically meant a countable tally of individual units, unlike "amount"'s original sense of an added-up total.
The real distinction
This pair follows the identical countable/uncountable logic as "much" versus "many" and "fewer" versus "less": "amount" pairs with uncountable nouns (amount of water, amount of patience, amount of money as an uncountable sum), while "number" pairs with countable nouns (number of bottles, number of people, number of dollars as individual bills). The word "money" itself is a useful illustration of how subtly this rule can bite: "money" is grammatically uncountable in English ("a large amount of money"), even though the actual dollars or coins it refers to are perfectly countable, a case that fools writers who judge the rule by real-world countability instead of checking the noun's actual grammatical category. Retail and marketing copy is a particularly frequent source of this error ("a large amount of customers" instead of the correct "a large number of customers"), likely because "amount" sounds slightly more impressive or formal to some writers even when the noun it's paired with is clearly countable. Because this rule is purely grammatical rather than about real-world logic, the test that works best is mechanical: try inserting a specific number directly before the noun in question — if that sounds natural, the noun is countable and needs "number"; if inserting a number sounds broken, the noun is uncountable and needs "amount." This same countable/uncountable logic connects amount/number to the much/many and fewer/less pairs elsewhere on this site, and writers who internalize the rule for one pair usually find the other two fall into place quickly, since all three rest on the identical underlying grammatical distinction rather than three separate rules to memorize. Financial writing offers a particularly instructive edge case: "amount" correctly describes an uncountable sum of money ("a large amount of money was raised"), while "number" correctly describes a countable tally of transactions, donors, or invoices ("a large number of donors contributed") — the same underlying event, a fundraiser, can require either word depending on which specific noun the sentence is actually quantifying.
Examples with “amount”
- The amount of rainfall this year has been unusual.
- She spent a huge amount of time on the project.
- The amount of effort required surprised everyone.
- There's a small amount of sugar left in the jar.
- The amount of debt has grown steadily each year.
- We were impressed by the amount of detail in the report.
- The amount of traffic today was unusually light.
- A fair amount of patience is needed for this job.
Examples with “number”
- The number of applicants doubled this year.
- A large number of customers complained about the delay.
- The number of errors dropped significantly after the update.
- Only a small number of seats remain for the concert.
- The number of employees has grown steadily.
- A growing number of people are working remotely.
- The number of accidents decreased after the new signage.
- A surprising number of students chose that elective.
Memory trick
Think of "number" as literally containing countable numerals — one, two, three — while "amount" evokes a single poured-together total, like water filling a glass, with no natural individual units to count. One more useful check: try slotting a specific number directly in front of the noun in question; if it fits naturally, you need "number," and if it sounds wrong, you need "amount" instead.