二 (èr) vs 两 (liǎng) in Chinese
二 / 两
Both 二 and 两 mean two, but they occupy different basic number patterns. Use 二 when counting, reading digits, forming ordinals, or building numbers such as 十二 and 二十. Use 两 before a measure word or many unit words: 两个人, 两本书, and 两百. The following word determines the choice.
Published July 23, 2026
Reviewed July 23, 2026
01 / PATTERN
See the Structure
MODEL
二 for counting and ordinals; 两 + Measure Word + Noun
Read the structure
Both 二 and 两 mean two, but they occupy different basic number patterns. Use 二 when counting, reading digits, forming ordinals, or building numbers such as 十二 and 二十. Use 两 before a measure word or many unit words: 两个人, 两本书, and 两百. The following word determines the choice. Keep the model 二 for counting and ordinals; 两 + Measure Word + Noun visible while you compare each sentence.
我有两个妹妹。
I have two younger sisters.
Choose the right context
Use 二 in counting, ordinals, and compound numbers: 一、二、三, 第二, and 二十。 Use 两 before an ordinary measure word: 两本书 and 两个人。 Use 两 before many large unit words in beginner speech: 两百 and 两千。
我买了两本书。
I bought two books.
Respect the boundary
Do not use 二 directly before an ordinary classifier in the basic pattern. Do not use 两 after 第 or inside 十二, 二十, or a digit-by-digit telephone number. Do not assume every occurrence of English 'two' has one fixed Chinese form.
我排在第两个。
(I am in the two-th place.)
Repair the pattern
两 used after the ordinal marker 第: Ordinal numbers use 第 + 二, so the fixed form is 第二个. 两 cannot replace 二 after 第. 两 used to build the number twenty: The number twenty is the fixed compound 二十. 两 cannot replace 二 inside this compound number.
我排在第二个。
Use the repaired structure without changing the intended meaning.
02 / MAP
Read the Sentence
Read from left to right and notice the job performed by each part. The labels describe this example; they are not a rule that every Chinese sentence must copy.
我有两个妹妹。
I have two younger sisters.
我有
二 for counting and ordinals; 两
This part occupies the 二 for counting and ordinals; 两 position in the model pattern.
两
Measure Word
This part occupies the Measure Word position in the model pattern.
个
Noun
This part occupies the Noun position in the model pattern.
妹妹
二 for counting and ordinals; 两
This part occupies the 二 for counting and ordinals; 两 position in the model pattern.
03 / EXAMPLES
Examples You Can Reuse
Keep the structure stable while changing the people, objects, times, or conditions. Pinyin is shown as reading support; use the Chinese sentence and translation to confirm the grammar relationship.
我有两个妹妹。
I have two younger sisters.
我买了两本书。
I bought two books.
我们班有二十个学生。
Our class has twenty students.
04 / LIMITS
When to Use It — and When Not To
Use it when
- Use 二 in counting, ordinals, and compound numbers: 一、二、三, 第二, and 二十。
- Use 两 before an ordinary measure word: 两本书 and 两个人。
- Use 两 before many large unit words in beginner speech: 两百 and 两千。
Do not use it when
- Do not use 二 directly before an ordinary classifier in the basic pattern.
- Do not use 两 after 第 or inside 十二, 二十, or a digit-by-digit telephone number.
- Do not assume every occurrence of English 'two' has one fixed Chinese form.
05 / REPAIR
Compare Right and Wrong
Compare the smallest meaningful change. Each explanation identifies a placement, scope, form, or clause relationship instead of treating the whole sentence as one undifferentiated mistake.
我排在第两个。
我排在第二个。
两 used after the ordinal marker 第
Ordinal numbers use 第 + 二, so the fixed form is 第二个. 两 cannot replace 二 after 第.
这里有两十个人。
这里有二十个人。
两 used to build the number twenty
The number twenty is the fixed compound 二十. 两 cannot replace 二 inside this compound number.
我排在第两个。
Ordinal numbers use 第 + 二, so the fixed form is 第二个. 两 cannot replace 二 after 第.
这里有两十个人。
The number twenty is the fixed compound 二十. 两 cannot replace 二 inside this compound number.
06 / PRACTICE
Practice the Grammar Point
Complete three short tasks in order: judge the pattern, repair a common error, and build the sentence. Feedback is fixed and reviewed, so these activities do not use a checker allowance.
1. Judge the sentence
2. Choose the correction
3. Build the sentence
Build a complete sentence with 二 / 两.
07 / APPLY
Apply It in Your Sentence
Write one original sentence with 二 / 两. Your draft moves to the checker through this browser session, selects this grammar point as the first review focus, and waits for you to submit.
08 / QUESTIONS
二 (èr) vs 两 (liǎng) Questions
Why is two people 两个人, not 二个人?
Because 个 is a classifier. In the basic quantity pattern, the form for two before a classifier is 两.
Why is twenty 二十, not 两十?
Compound numbers from twenty upward are built with 二 before 十. 两 is used before classifiers and many larger unit words, not inside 二十.
09 / SOURCES
Sources and Review Notes
These references support different parts of the lesson. GF0025-2021 supports level placement only; professional grammar works support the explanation, limits, examples, and cross-checks. Their inclusion does not imply endorsement.
Chinese Proficiency Grading Standards for International Chinese Language Education (GF0025-2021)
Ministry of Education and State Language Commission · Ministry of Education of the PRC · 2021
Locator: Appendix A, A.1.1.4 数词, 【一07】一、二/两…
Supports placement in HSK 1; it does not independently establish the usage explanation.
Official sourceModern Mandarin Chinese Grammar: A Practical Guide, 3rd ed.
Ross, Ma, Chen, He and Yeh · Routledge · 2024
Locator: §6.1.1–§6.1.3, §6.4, and §9.1 (forms of two, ordinals, and classifier phrases)
二 is used for counting, compound numbers, and ordinals, while 两 is used before classifiers in quantity phrases.
Official source10 / CONTINUE
Continue with a Connected Rule
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个Chinese Measure Words
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概数表示法2Approximate Numbers with Adverbs, Adjacent Numerals, and Postpositions
Apply numeral selection inside a broader set of approximate-number expressions.
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