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	🇨🇳 中文 规则	Example	🇨🇳 中文 示例
Use fewer + plural count noun	🧩 使用较少 + 复数可数名词	Fewer cars are on the road today.	🧩 今天路上汽车的数量较少。
Use fewer when the focus is on number of items	🧩 当关注点在物件数量时	We had fewer meetings this month.	🧩 本月我们开会的次数更少。
Use fewer with things measured as units	🧩 用于按单位计量的事物	The recipe uses fewer ingredients.	🧩 食谱使用的配料更少。

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	🇨🇳 中文 规则	Example	🇨🇳 中文 示例
Use less + uncountable noun	🧩 使用 less + 不可数名词	I have less patience today.	🧩 我今天的耐心更少。
Use less for amount, degree, or intensity	🧩 在数量、程度或强度上使用 less	This version is less expensive.	🧩 这个版本更便宜。
Use less with singular abstract nouns	🧩 对单数抽象名词使用 less	We need less information and more clarity.	🧩 我们需要更少的信息，以获得更清晰的表达。

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	🇨🇳 中文 规则	Example	🇨🇳 中文 示例
less + adjective	🧩 less + 形容词	The second exam was less difficult.	🧩 第二次考试不那么困难。
less + adverb	🧩 less + 副词	She travels less often now.	🧩 她现在旅行得更少。
less + noun phrase showing degree	🧩 less + 表示程度的名词短语	He spoke with less confidence.	🧩 他讲话时自信心更少。

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	🇨🇳 中文 规则	Example	🇨🇳 中文 示例
Less is common with time treated as one amount	🧩 将时间视为一个整体时，less 常见	It takes less than two hours.	🧩 少于两小时。
Less is common with money treated as one sum	🧩 将钱视为一个总额时，less 常见	It costs less than ten dollars.	🧩 成本少于十美元。
Less is common with distance treated as one span	🧩 将距离视为一个跨度时，less 常见	It is less than five miles away.	🧩 离这里不到五英里。

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	🇨🇳 中文 规则	Example	🇨🇳 中文 示例
fewer than + plural count noun	🧩 fewer than + 复数可数名词	Fewer than 20 students attended.	🧩 少于 20 名学生出席。
less than + uncountable noun	🧩 less than + 不可数名词	Less than half the water remained.	🧩 不到一半的水仍然存在。
less than + adjective or adverb	🧩 less than + 形容词或副词	The new plan is less than ideal.	🧩 新计划尚未达到理想状态。

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	🇨🇳 中文 词/短语	Definition	🇨🇳 中文 定义	Example	🇨🇳 中文 示例
paper	🧩 paper	Countable sheets or uncountable material	🧩 可数的纸张或不可数材料	Fewer papers were submitted.	🧩 提交的纸张数量较少。
coffee	🧩 coffee	Countable servings or uncountable drink	🧩 可数的份量或不可数的饮品	I drink less coffee now.	🧩 我现在喝咖啡更少。
experience	🧩 experience	Countable events or uncountable skill	🧩 可数的事件或不可数的技能	She has less experience in management.	🧩 他在管理方面的经验更少。
time	🧩 time	Countable occasions or uncountable duration	🧩 可数的场合或不可数的时长	We made fewer trips and spent less time traveling.	🧩 我们出行次数减少，花在旅行上的时间也更少。

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	🇨🇳 中文 规则	Example	🇨🇳 中文 示例
Formal preference: fewer with count nouns	🧩 正式偏好：可数名词使用 fewer	Fewer than 50 employees responded.	🧩 少于 50 名员工作出回应。
Casual usage: less with count nouns in totals	🧩 口语用法：在总量时对可数名词使用 less	There are less cars here today.	🧩 今天这里的汽车数量较少。
For polished writing, avoid less + plural count noun	🧩 为精炼写作，避免 less + 复数可数名词	Use fewer people, not less people.	🧩 应使用 fewer 的人，不要使用 less 的人。

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	🇨🇳 中文 规则	Example	🇨🇳 中文 示例
How many items	🧩 物品数量	fewer messages	🧩 更少的消息
How much amount or degree	🧩 多少数量或程度	less noise	🧩 更少的噪音
Measured total phrasing often uses less	🧩 总量表达通常使用 less	less than three minutes	🧩 少于三分钟