When do you use 'less' and when do you use 'fewer'?

The rule:

• "Fewer people came than expected."
• "Fewer than five mistakes."
• "I have fewer books than she does."

• "Less water."
• "Less time."
• "Less traffic."
• "Less money." (money is measured, not counted individually)

The test: Can you count individual units? Fewer people (1 person, 2 people). Can't count individual units? Less water (not "one water, two waters").

The supermarket sign problem: "10 items or less" is technically incorrect — it should be "10 items or fewer." Most native speakers don't notice or care.

Exception: Time and distance often use "less" even though they're technically countable: "less than five minutes," "less than three miles." This is standard and accepted.

Register: The fewer/less distinction matters in formal writing. In casual speech, "less" is commonly used for both.

Tags: grammar, countable nouns, common mistakes, writing