Both words mean "a smaller amount", so it's easy to mix them up. The difference is what you're talking about.
- Fewer is for things you can count: fewer apples, fewer mistakes.
- Less is for amounts you can't count: less milk, less noise.
Fewer: things you can count
Use fewer with plural nouns, the kind you can count one by one: one cookie, two cookies, three cookies.
We have fewer problems today than yesterday.
There are fewer students in class because of the school trip.
My goldfish ate fewer crumbs this week. He's on a diet, and he's furious.
It goes with than when you compare: fewer than ten.
Less: amounts you can't count
Use less with things you measure or pile up rather than count: milk, sugar, noise, time, homework.
I'd like less sugar in my tea, please.
There's less traffic on Sundays.
We have less homework tonight, so the whole class is smiling.
It also goes with than: less than a litre.
Easy way to tell them apart
Try counting out loud: "one, two, three…"
- Works? Use fewer. One cookie, two cookies, so fewer cookies.
- Sounds silly? Use less. One milk, two milks? So less milk.
💡 The OddLingo Trick
Fewer has the word few hiding inside it, and few is for things you can count: a few grapes.
Less is for stuff you pour, pile or stretch: milk, sand, noise, time.
⚠️ Common mistakes
Can you count them? Use fewer.
❌ We made less mistakes this time.
✅ We made fewer mistakes this time.
Can't count it? Use less.
❌ There's fewer traffic today.
✅ There's less traffic today.
Mixing them in one sentence. Each one gets its own job.
❌ I want less pencils and fewer glue.
✅ I want fewer pencils and less glue.
📌 Good to know
Time, money, distance and weight are treated as amounts, even though you can count the units. So less is normal there:
We have less than ten minutes.
It costs less than five dollars.
It's less than a mile to school.
There's also the famous supermarket sign: "10 items or less". Many people say it should be fewer. Merriam-Webster treats or less as standard in limit phrases like this, so you will see both. In your own school writing, fewer items is the safe choice.
Both words go with than when you compare, as in fewer than ten and less than ten. If you sometimes mix up than and then, read Then vs Than.
🕵️ Where did the rule come from?
The rule that fewer is for counting is often traced to a writer named Robert Baker, who wrote in 1770 that he thought fewer sounded better. It was his own preference. Later writers turned it into a rule.
But less had been used with countable things for a very long time before that. So the rule is real and useful for school, and it's also a good example of how English works: part rule, part habit, part opinion.
💬 In a conversation
Mia: The sign says "10 items or less", and I have eleven.
Tom: Then you need a different till.
Mia: Or fewer snacks.
Tom: Nobody wants fewer snacks.