When do I use 只 vs 光?

Use 只 as the default in any situation – it is neutral and safe for all registers. Use 光 only in informal, spoken Chinese when you want to emphasize that someone does nothing except a certain action, often with a critical or dismissive tone. In doubt, choose 只.

Can 光 be used in a positive or praising way?

Rarely. 光 usually carries a negative nuance (limiting to something trivial). A sentence like 他光学习 (tā guāng xuéxí) 'He only studies' sounds like a complaint that he doesn’t do anything else. For a neutral or positive statement, use 只 (他只学习).

How do I say 'not only' with these words?

Use 不只 (bùzhǐ) for neutral, all-register contexts, and 不光 (bùguāng) for colloquial speech. Both are neutral in tone – 不光 does not carry a complaining sense. Example: 他不只聪明，而且勤奋 (tā bùzhǐ cōngmíng, érqiě qínfèn) or 他不光聪明，而且勤奋.

Is 光 ever used before a noun?

No. Like 只, 光 is an adverb and must be followed by a verb, not a noun. To restrict a noun, you need a verb or a special structure: 光 + verb is fine; 光 + noun is ungrammatical. For noun restrictions, use 只有 (only have) or 只是 (it's just).

Easily confusedHSK 4

只 vs 光 (zhǐ vs guāng): two ways to say “only” in Chinese

Both 只 and 光 mean 'only', but they differ in register and nuance. 只 is the standard, neutral adverb used in most contexts, including formal writing and speech. 光 is more colloquial and often carries a sense of 'nothing but' or 'merely', sometimes implying criticism or dissatisfaction. Choosing between them depends on the tone and formality of the situation.

Both 只 (zhǐ) and 光 (guāng) are adverbs that restrict the scope of an action or situation, meaning 'only'. 只 is the default, neutral choice, appropriate in both spoken and written Chinese, and is the one learners should use first. 光 is less formal and adds a subjective flavor, often used to complain or emphasize that someone is doing nothing except a particular thing. The two overlap in many informal contexts, but 光 cannot be used in formal or impersonal writing. Additionally, only 只 appears in the fixed structures 只有 (zhǐyǒu, 'only have/if only') and 只是 (zhǐshì, 'only is/just').

When to use each

只zhǐ

only

Use 只 as the standard, neutral adverb to restrict a verb or verb phrase. It works in all registers—conversation, writing, formal announcements. For example, only drink water: 只喝水 (zhǐ hē shuǐ). To restrict a noun phrase, combine 只 with 有: 只有 (zhǐyǒu) 'only have'. 只 also forms the common expression 只是 (zhǐshì) 'it's just that'.

When the context is neutral or objective, 只 is the only natural choice. In negative constructions, 不只 (bùzhǐ) means 'not only' and is neutral in tone.

光guāng

only, merely

Use 光 in informal, spoken Chinese to emphasize that something is limited to one, often trivial, activity or thing. It carries a tone of disapproval, dissatisfaction, or dismissiveness, as in 光说不做 (guāng shuō bù zuò) 'only talk but no action'. In casual positive statements it can mean 'merely', but with a slight flattening effect.

光 is not used in formal writing or polite requests. In the negative form 不光 (bùguāng) – meaning 'not only' – the tone is neutral and simply colloquial, not inherently complaining. Overusing 光 in neutral contexts can sound judgmental.

At a glance

	只	光
Register	Formal and informal, written and spoken	Informal, conversational only
Tone	Neutral, objective	Subjective, often critical or dismissive
Modifying nouns directly	Cannot; requires 有 (只有)	Cannot; also requires 有 (但有光有的情况极少); in practice 光 is not used to modify nouns
Common fixed forms	只有 (only have), 只是 (only/just)	None; 光 is typically used as a bare adverb
Negative 'not only'	不只 (bùzhǐ) – neutral, suitable for all contexts	不光 (bùguāng) – colloquial, neutral tone

Examples

只
我只喝咖啡，不喝茶。
Wǒ zhǐ hē kāfēi, bù hē chá.
I only drink coffee, not tea.
Only modifies the verb 喝, not a noun. Natural neutral statement.
光
他光说不做，没人喜欢他。
Tā guāng shuō bù zuò, méi rén xǐhuān tā.
He only talks and doesn't act; nobody likes him.
Critical tone – typical use of 光 in a complaint.
只
不只学生，老师也参加了。
Bùzhǐ xuéshēng, lǎoshī yě cānjiā le.
Not only students, but also teachers participated.
Negative of 只: 不只 is neutral and can be used in writing.
光
不光学生，老师也参加了。
Bùguāng xuéshēng, lǎoshī yě cānjiā le.
Not only students, but also teachers participated.
Negative of 光: 不光 is colloquial but neutral, not complaining.
只
只有会员才能进入。
Zhǐyǒu huìyuán cáinéng jìnrù.
Only members can enter.
To restrict a noun, use 只有 (不能仅用只).
光
他光想着玩，忘了做作业。
Tā guāng xiǎng zhe wán, wàng le zuò zuòyè.
He only thought about playing and forgot to do homework.
光 emphasizes that his mind was solely on playing – slightly critical.

Common mistakes

Using 只 directly before a noun: ✗ 只咖啡 (zhǐ kāfēi). Always use 只有 or 只是: 只有咖啡 or 只是咖啡.
Using 光 in formal writing or polite requests: ✗ 光请进来 (guāng qǐng jìnlái). Use 只, e.g., 只请进来 (zhǐ qǐng jìnlái).
Assuming 光 always has a complaining tone: 不光 is neutral; in positive sentences like 我光吃面不吃饭 (wǒ guāng chī miàn bù chī fàn) it can be a simple fact with a light dismissive tone.
Overusing 光 in neutral statements where 只 is more appropriate, e.g., 我光喝水 (wǒ guāng hē shuǐ) implies criticism of only drinking water, while 我只喝水 is neutral.
Using 只有 when you mean 只 with a verb: ✗ 我只有喝咖啡 (wǒ zhǐyǒu hē kāfēi) would mean 'I only have coffee to drink' (possession), not 'I only drink coffee'. Correct: 我只喝咖啡.

FAQ

When do I use 只 vs 光?: Use 只 as the default in any situation – it is neutral and safe for all registers. Use 光 only in informal, spoken Chinese when you want to emphasize that someone does nothing except a certain action, often with a critical or dismissive tone. In doubt, choose 只.
Can 光 be used in a positive or praising way?: Rarely. 光 usually carries a negative nuance (limiting to something trivial). A sentence like 他光学习 (tā guāng xuéxí) 'He only studies' sounds like a complaint that he doesn’t do anything else. For a neutral or positive statement, use 只 (他只学习).
How do I say 'not only' with these words?: Use 不只 (bùzhǐ) for neutral, all-register contexts, and 不光 (bùguāng) for colloquial speech. Both are neutral in tone – 不光 does not carry a complaining sense. Example: 他不只聪明，而且勤奋 (tā bùzhǐ cōngmíng, érqiě qínfèn) or 他不光聪明，而且勤奋.
Is 光 ever used before a noun?: No. Like 只, 光 is an adverb and must be followed by a verb, not a noun. To restrict a noun, you need a verb or a special structure: 光 + verb is fine; 光 + noun is ungrammatical. For noun restrictions, use 只有 (only have) or 只是 (it's just).