Fewer vs less is one of the most frequently debated word choices in everyday English. The traditional rule sounds simple: use fewer for things you count, and less for things you measure. But supermarket signs that read "10 items or less" have put this rule under pressure for decades, and there are real exceptions worth knowing. Get the core distinction right, and most sentences will fall into place on their own.
The core rule: countable vs uncountable nouns
The difference between fewer and less comes down to the noun each word modifies. Fewer goes with countable nouns: things you can list individually, like tickets, errors, or people. Less goes with uncountable (or mass) nouns: things measured in bulk, like water, time, or sand.
- Fewer: fewer mistakes, fewer cars, fewer opportunities
- Less: less water, less time, less effort
The test is whether you can put a number directly in front of the noun. You can say "three mistakes" or "five cars," so those take fewer. You can't say "three waters" or "five efforts" as a count, so those take less. That's the whole rule in one sentence.
Why people get it wrong
English speakers reach for less as a default because it sounds more natural in casual speech. "Less people showed up" rolls off the tongue faster than "fewer people showed up," even though the second is correct. This is especially common before plural nouns in informal registers, where the grammar rule hasn't fully displaced habit.
The supermarket checkout sign is the most famous battleground. "10 items or less" appears in stores across the English-speaking world, and prescriptive grammarians have been correcting it to "10 items or fewer" for decades. The sign has become such a cultural flashpoint that the linguist Language Log dedicated multiple posts to its history. The short version: "10 items or less" has been in print since at least the 1970s, and most style guides now accept it as an established idiom even if they prefer "fewer."
The genuine edge cases
The countable vs uncountable rule handles the vast majority of sentences. A few situations genuinely complicate it.
Numbers and amounts treated as a single quantity. When a number refers to a total rather than individual units, less is standard. "Less than three miles" treats the distance as a quantity. "Less than 10 percent" treats the percentage as a measurement. You'd only reach for fewer if you were counting distinct individual things: "fewer than three attempts."
Time, money, and distance in singular expressions. "Less than five years," "less than £100," and "less than 20 miles" all use less correctly, even though years, pounds, and miles are countable in isolation. When you're talking about a span, a sum, or a measurement rather than discrete items, less is the right choice.
The phrase "one less." Almost everyone says "one less thing to worry about," not "one fewer thing to worry about." Technically fewer should win, since "things" are countable. But "one fewer" sounds awkward enough that most style guides quietly allow "one less" as an idiom.
Quick-reference: which word fits?
If you're unsure which word to use, ask yourself one question: can I count the noun as individual units? If yes, choose fewer. If the noun describes a mass, a measurement, or a single total, choose less. The cases below illustrate both sides clearly.
Correct uses of fewer: fewer applications, fewer delays, fewer calories (when counting individual calorie units). Correct uses of less: less sugar, less traffic, less than 500 calories (as a measurement). The calories example shows how the same noun can flip depending on whether you're counting discrete units or describing a bulk quantity.
What style guides say
Most authoritative style guides land in the same place. The Chicago Manual of Style, the Associated Press Stylebook, and Fowler's Modern English Usage all recommend fewer for countable nouns and less for uncountable ones, while acknowledging the exceptions above. None of them treat the rule as absolute. Fowler's in particular notes that less before plural nouns has a long history in English and shouldn't be treated as a modern corruption.
The prescriptive tradition goes back at least to 1770, when the English grammarian Robert Baker wrote that less should not be used for countable things. That note has been amplified in grammar guides ever since, which is why the rule feels so firm even though native speakers routinely bend it. Similar debates show up across grammar: the affect vs effect question follows the same pattern of a clear core rule surrounded by cases that require a second thought.
A note on register
In formal writing, the distinction matters. In conversation, it matters much less. If you use less with a countable noun in a job application, a legal document, or a published article, a careful reader will notice. In spoken English, especially in casual contexts, less before countable nouns is so common that correcting it can sound pedantic.
The practical advice: learn the rule so you can apply it when it counts. Use fewer with countable nouns in formal writing. Give yourself permission to relax in speech. And don't lose sleep over the supermarket sign. This is the same kind of judgment call that comes up in questions like alternate vs alternative, where a strict rule exists but context shapes what actually sounds right.
Summary
Use fewer when you're talking about things you can count as individual units: fewer errors, fewer tickets, fewer days. Use less when you're talking about quantities, measurements, or mass nouns: less time, less sugar, less than 50 miles. The exceptions (one less, less than a number used as a total, established idioms) are narrow enough that the base rule covers almost everything you'll write.