Mandarin has two different words for the number two.

You’ll need to know when to use èr (二) and when to use liǎng (两).

Using the wrong word is a very common mistake for beginners.

This guide will show you exactly which one to use in every situation.

When to use èr (二)

The word èr (二) is used for reading numbers in a mathematical sequence.

You’ll use it when counting up from zero just like you would in English.

It’s also the word you use for doing basic math or reading fractions.

Whenever you read a phone number, a room number, or a bus route, you must use èr.

You also use it for ordinal numbers to indicate a position or rank.

Any time you want to say “second”, you’ll use the prefix dì (第) followed by èr.

Compound numbers in the tens and twenties also strictly use èr.

You’ll say shí’èr (12) and èrshí (20).

When to use liǎng (两)

The word liǎng (两) is used to express a physical quantity of something.

You must use liǎng whenever a measure word follows the number two.

Measure words are mandatory in Mandarin when counting specific objects or people.

If you want to say “two apples” or “two people”, you can’t use èr.

You must use liǎng followed by the appropriate measure word.

Another very common time to use liǎng is when telling the time.

Saying “two o’clock” always requires liǎng.

You’ll also use it when talking about someone being two years of age.

Special exceptions for large numbers

Larger numbers follow a slightly different set of rules depending on the place value.

For the number 200, you can actually use either èrbǎi (二百) or liǎngbǎi (两百).

Both are completely grammatically correct and understood everywhere.

People in northern China tend to prefer èrbǎi, while southern speakers often use liǎngbǎi.

However, for the number 2,000, you’ll almost exclusively hear liǎngqiān (两千).

For 20,000, the standard phrasing is liǎngwàn (两万).

Summary table for er and liang

Here’s a simple table to help you memorize the rules for both words.