Use fewer with countable nouns you can separate into individual units, like apples, people, or emails. Use less with uncountable nouns that are treated as a single amount, like water, time, or traffic. This distinction is about how English normally measures the noun: as items or as an amount.

Fewer modifies plural count nouns and answers the idea of how many. It fits when you could realistically count the units one by one, even if you do not actually count them. It is common with numbers, plurals, and categories of things.

Rule	Example
Use fewer + plural count noun	Fewer cars are on the road today.
Use fewer when the focus is on number of items	We had fewer meetings this month.
Use fewer with things measured as units	The recipe uses fewer ingredients.

Less modifies uncountable nouns and answers the idea of how much. It fits when the noun is treated as a substance, quantity, or abstract amount rather than separate units. It is also common with adjectives and adverbs to compare degree or intensity.

Rule	Example
Use less + uncountable noun	I have less patience today.
Use less for amount, degree, or intensity	This version is less expensive.
Use less with singular abstract nouns	We need less information and more clarity.

Less is the normal comparative for describing a lower degree of an adjective or adverb. In these cases, fewer is not possible because you are not counting units, you are comparing intensity. This use is very common in both formal and informal English.

Rule	Example
less + adjective	The second exam was less difficult.
less + adverb	She travels less often now.
less + noun phrase showing degree	He spoke with less confidence.

In everyday English, less is often used with things that are technically countable when they are seen as a single measurement or total amount. This is especially common with money, time, distance, and other quantities that people experience as one whole. Formal writing sometimes prefers fewer in these cases, but less is widely accepted in speech.

Rule	Example
Less is common with time treated as one amount	It takes less than two hours.
Less is common with money treated as one sum	It costs less than ten dollars.
Less is common with distance treated as one span	It is less than five miles away.

Both fewer and less frequently appear in comparisons with than. Choose based on the noun that follows: plural count nouns generally take fewer, and uncountable nouns generally take less. If the comparison is about degree instead of number, use less.

Rule	Example
fewer than + plural count noun	Fewer than 20 students attended.
less than + uncountable noun	Less than half the water remained.
less than + adjective or adverb	The new plan is less than ideal.

Some nouns can be countable or uncountable depending on meaning. When you mean individual items, use fewer; when you mean an amount or an abstract total, use less. Pay attention to whether the speaker is counting units or describing quantity as a whole.

Word/Phrase	Definition	Example
paper	Countable sheets or uncountable material	Fewer papers were submitted.
coffee	Countable servings or uncountable drink	I drink less coffee now.
experience	Countable events or uncountable skill	She has less experience in management.
time	Countable occasions or uncountable duration	We made fewer trips and spent less time traveling.

In formal writing and careful editing, fewer is preferred with plural count nouns, even when they are part of a measurement-like phrase. In casual speech and many public signs, less may appear with count nouns, and listeners usually accept it. If you want the safest choice for tests or formal style, follow the count versus mass guideline strictly.

Rule	Example
Formal preference: fewer with count nouns	Fewer than 50 employees responded.
Casual usage: less with count nouns in totals	There are less cars here today.
For polished writing, avoid less + plural count noun	Use fewer people, not less people.

Decide by asking what you are comparing. If it is a number of separate units, choose fewer. If it is an amount, degree, or an uncountable substance or abstract quantity, choose less. When a countable thing is treated as one measured total, less is common, but fewer is the conservative formal option.

Rule	Example
How many items	fewer messages
How much amount or degree	less noise
Measured total phrasing often uses less	less than three minutes