二 vs 两

English has one word, "two," that covers everything: the abstract digit, the position in a sequence, and the quantity of some object. Chinese splits that job between two words — 二 (èr) and 两 (liǎng) — and choosing wrong is one of the most immediately noticeable beginner errors, on par with dropping a measure word. The good news is that the split follows a clean logic once you see it: 二 is the number as a label or digit; 两 is the number as a count of things. Learn that distinction and nearly every case decides itself.

The core split: label vs. count

Think of 二 as the "two" you write on a page or say when reciting — the pure digit, the ordinal, the mathematical value. Think of 两 as the "two" that answers how many things? — it points at a quantity and almost always has a measure word (or a big place word) right behind it.

The clock example is the classic trap: "two o'clock" is 两点 (liǎng diǎn), because you are counting two hours-worth on the clock — but the month "February" is 二月 (èr yuè) and the day "the 2nd" is 二号 (èr hào), because those are ordinals, labels for a position. Same "two," three different words, all in a sentence a learner uses on day one.

Before a measure word: always 两

This is the most reliable rule of all, so lock it in first. When "two" sits directly in front of a measure word, it is 两, one hundred percent of the time. 两个 (two, general), 两本 (two books), 两杯 (two cups), 两次 (two times) — never 二个, never 二本.

This rule quietly extends to time words that are themselves measure words — 两天 (two days), 两年 (two years), 两个星期 (two weeks) — because 天 and 年 count directly like measure words. Compare 二月 (February, an ordinal label) with 两个月 (two months, a counted duration): the first is a name, the second is a quantity.

Before big place words: 两 leads, 二 lives inside

When "two" is the leading digit before 百, 千, 万 or 亿, use 两: 两百 (200), 两千 (2,000), 两万 (20,000), 两亿 (200 million). But when the "two" is a digit sitting inside a longer number — in the tens place, or a hundred that follows a bigger unit — it reverts to 二, because there it is just a digit, not a leading count.

So 22 is 二十二 (èrshí'èr) — both twos are 二, because one is the tens digit and one is the units digit, neither a leading count before a place word. And 120 is 一百二十 (yìbǎi èrshí) — the 二 is the tens digit. The single genuinely fuzzy case is a standalone 200: both 两百 and 二百 (èrbǎi) are correct, with 两百 more common in the south and standard teaching, 二百 more common in the north. Don't lose sleep over that one; before 千/万/亿 the choice is firmly 两.

There is even a fossilized idiom worth knowing: 二百五 (èrbǎiwǔ), literally "250," is slang for a foolish, reckless person — a rare case where the number itself carries meaning. It keeps 二 because it's a fixed digit-string, not a live count.

Common Mistakes

1. Using 二 before a measure word. The number-one 二/两 error — before any measure word it must be 两.

2. Saying 两 for a floor, month, or ordinal. Positions and labels take 二.

3. Saying 二点 for two o'clock. The clock counts hours, so it's 两点.

4. Using 二 before 千/万. A leading "two" before these place words is 两.

Key Takeaways

• 二 (èr) is the number as a label or digit: counting aloud, tens (二十, 十二), ordinals (第二, 二楼), dates (二月, 二号), years, decimals, arithmetic.
• 两 (liǎng) is the number as a count of things: always before a measure word (两个, 两本), and for durations (两天, 两年).
• Before 千/万/亿 a leading "two" is 两 (两千, 两万, 两亿); a "two" buried inside a number stays 二 (二十二, 一百二十).
• Standalone 200 allows both 两百 and 二百 — the only genuinely optional case.
• The clock is 两点, but the month and the date are 二月 / 二号 — count vs. label in a single breath.