Understanding when to use less versus fewer can be tricky, even for native English speakers.

Fewer versus less: the basic rule

The general basic rule is fairly simple: use fewer for countable nouns and less for uncountable nouns.

For example:

• Fewer sugar cubes, but less sugar
• Fewer advertisements, but less advertising
• Fewer grains of rice, but less rice

Nouns like rice, sand, and advertising are uncountable, so we use less. For plural countable nouns like cubes, birds, or grains, we use fewer. Even if the plural form looks the same as the singular (such as for herd animals such as deer or sheep), or takes a special form like mice, the rule still applies: use fewer.

Fewer deer
Fewer sheep
Fewer mice

Note that for talking about increasing quantities we do not have this problem.
We use more for both countable and uncountable.

More sugar cubes and more sugar
More advertisements and more advertising

Notable exceptions

However, although we have this general rule regarding countables and uncountables, there are some notable exceptions.

We use less with the number “one”

✅ One less problem
✅ One car less

We also use less with measurements and amounts

✅ 6 miles less,  €10 less, or six months less

In phrases where a number is treated as a single quantity or measurement, less is often preferred.

Take for example the supermarket sign: “10 items or less.” Strict grammarians argue it should be “10 items or fewer”, since items are countable. However, it is more common English usage to say “10 items or less” as the word” items” is treated as a unit or measurement.

Changes in use

Interestingly, there’s also a growing trend toward using less with some plural nouns, perhaps influenced by second-language speakers and evolving usage. This is particularly common with irregular plurals that do not have a “-s” ending plural. Today, using a phrase  such as “less people”  or “less children” in informal use may no longer raise eyebrows, whereas a standard “-s” ending plural with “less” would sound strange. Note that in formal situations fewer is the correct choice.

Language evolves—and while the fewer vs. less rules are helpful, context and common usage matter too. If you have further questions about this grammar question or any other grammar points please contact Galimatias by clicking the button below.