How to Say "I Know" in Chinese

The usual way to say “I know” is 我知道 (wǒ zhīdào). It is used for knowing a fact or piece of information; use 认识 only for knowing a person or place.

The most common way

wǒ zhīdào

I know (a fact or piece of information).

How to say it: Make both syllables clear: zhī has a high, level tone and dào falls sharply; the zh is a curled-tongue sound, not the English j.

casual
wǒ zhīdào la
I know already; often friendly but can sound slightly impatient.
When to use it: Use it with friends or family when someone is reminding you of something you already know.
regional
wǒ xiǎode
I know; a more colloquial form common in southern Mandarin.
When to use it: Use it in informal speech, especially in southern China or with people who speak that way.
understanding
wǒ dǒng
I get it; I understand the point, not just the facts.
When to use it: Use it when someone explains a situation or feeling and you want to show you understand.
brief acknowledgment
míngbai
Got it; understood.
When to use it: Use it as a short reply to instructions or an explanation, often at work or in service situations.
work chat
shōudào
Received; roger that; I’ve got the message.
When to use it: Use it in text or work chats to confirm you have received instructions or information.

A
？
Nǐ jìde míngtiān jiǔ diǎn kāihuì ma?
Do you remember the meeting tomorrow at nine?
B
，。
Wǒ zhīdào la, nǐ yǐjīng shuō le sān biàn le.
I know, you’ve already said it three times.
A
，。
Hǎo, nà jiù bié chídào.
Okay, then don’t be late.

~~我认识。~~ → 我知道。
认识 means to know or be acquainted with a person or place, not to know a fact.