When do I use 是 vs 在?

Use 是 to state what something is (identity/classification). Use 在 to state where something is (location). For example, '他是老师' (He is a teacher) uses 是; '他在学校' (He is at school) uses 在.

Can I use 是 to say where I am?

No. 是 requires a noun complement, not a place. To say where you are, always use 在: '我在这里' (I am here), not '我是这里'.

What question words go with 是 and 在?

For 是, use 什么 ('what') or 谁 ('who') to ask about identity: '你是谁？' (Who are you?). For 在, use 哪儿 ('where') to ask about location: '你在哪儿？' (Where are you?).

Is it ever correct to use 是 with an adjective?

Yes, but only for emphasis or contrast. In a simple statement like '她很漂亮' (She is pretty), 是 is omitted. To emphasize, you can say '她是漂亮' (She is indeed pretty). This is grammatically correct, though less common in everyday speech.

Easily confusedHSK 1

是 vs 在 (shì vs zài): identity vs location

是 (shì) is a copula that links a subject to a noun or noun phrase to express identity or classification. 在 (zài) indicates the location or existence of a person or thing. Use 是 for 'to be something' and 在 for 'to be at a place'. A common mistake is using 是 for location (e.g., '我是这里'), which requires 在.

是 and 在 are both translated as 'to be' but serve different functions. 是 acts as a copula that equates the subject with a noun phrase, such as in '我是学生' (I am a student). 在 functions as a verb indicating location, as in '我在家' (I am at home). The core distinction: 是 identifies; 在 locates. Using 是 where a location is meant (e.g., '我是这里') is a common error because 是 requires a noun complement, not a place phrase.

使い分け

是shì

to be (identity)

Use 是 to identify, classify, or define a subject with a noun or noun phrase. It corresponds to English 'be' in equational sentences: A is B (e.g., nationality, profession, object identity). 是 can also precede adjectives for emphasis (e.g., '她是很好' – she is indeed good), but in neutral descriptions the adjective alone suffices (e.g., '她很好').

是 is not required before adjectives in simple statements; using it there adds an emphatic or contrastive nuance. The basic pattern for adjectives is Subject + (很 +) Adjective.

在zài

be located at

Use 在 to state where a person, object, or scheduled event is located. It always takes a place phrase (e.g., 家, 学校, 这里) or, for events only, a time phrase (e.g., '会议在三点'). For personal location, only use 在 with a place; '我在三点' is ungrammatical. 在 can also indicate being engaged in an activity (e.g., '他在开会' – he is in a meeting).

在 can be followed by a verb phrase to express progressive aspect (e.g., '他在吃饭' – he is eating), but this is a separate grammatical use from the location meaning.

ひと目で分かる

	是	在
Core meaning	Links subject to a noun (A is B)	Indicates location (A is at place)
Required complement	Noun or noun phrase (identity/classification)	Place phrase (e.g., 家, 学校, 这里)
Negation	不是 (bù shì)	不在 (bù zài)
Question form	什么 (shénme) – identity: '你是谁？'	哪儿 (nǎr) – location: '你在哪儿？'

例文

是
我是学生。
Wǒ shì xué shēng.
I am a student.
Identity: subject classified as a student.
是
她是中国人。
Tā shì zhōng guó rén.
She is Chinese.
Nationality: she belongs to the category 'Chinese person'.
是
她是很好，但是不够美。
Tā shì hěn hǎo, dàn shì bú gòu měi.
She is indeed good, but not beautiful enough.
Emphatic use of 是 before adjective; correct for contrast/emphasis.
在
我在家。
Wǒ zài jiā.
I am at home.
Location: indicates where the subject is.
在
猫在桌子上。
Māo zài zhuō zi shàng.
The cat is on the table.
Specific location with positional word '上'.
在
会议在三点。
Huì yì zài sān diǎn.
The meeting is at 3 o'clock.
Time for scheduled events; not for personal location (e.g., '我在三点' is wrong).

よくある間違い

Using 是 for location: '我是这里' → correct: '我在这里' (I am here).
Using 在 for identity: '我在学生' → correct: '我是学生' (I am a student).
Omitting 在 in location sentences: '我家北京' → correct: '我家在北京' (My home is in Beijing).

よくある質問

When do I use 是 vs 在?: Use 是 to state what something is (identity/classification). Use 在 to state where something is (location). For example, '他是老师' (He is a teacher) uses 是; '他在学校' (He is at school) uses 在.
Can I use 是 to say where I am?: No. 是 requires a noun complement, not a place. To say where you are, always use 在: '我在这里' (I am here), not '我是这里'.
What question words go with 是 and 在?: For 是, use 什么 ('what') or 谁 ('who') to ask about identity: '你是谁？' (Who are you?). For 在, use 哪儿 ('where') to ask about location: '你在哪儿？' (Where are you?).
Is it ever correct to use 是 with an adjective?: Yes, but only for emphasis or contrast. In a simple statement like '她很漂亮' (She is pretty), 是 is omitted. To emphasize, you can say '她是漂亮' (She is indeed pretty). This is grammatically correct, though less common in everyday speech.