Quick answer: 累 is tired, 困 is sleepy
English “tired” covers two different states, and Chinese separates them. 累 (lèi) is tired from exertion — after work, sport, travel or a long day. 困 (kùn) is sleepy — you need to sleep, and you might yawn or have trouble keeping your eyes open. Choosing the wrong one is one of the most common beginner mistakes in Chinese.
If someone asks you why you are quiet at a party, 我很累 explains a long day. If you are falling asleep at your desk, 我很困 is the accurate word. 有点困 means “a bit sleepy”.
| Chinese | Pinyin | Meaning | Register and use |
|---|---|---|---|
| 累 | lèi | Tired from exertion | Everyday; the default word |
| 困 | kùn | Sleepy | Everyday; you need sleep |
| 我很累 | wǒ hěn lèi | I am very tired | States the degree |
| 我累了 | wǒ lèi le | I am tired now | States the change |
| 累死了 | lèi sǐ le | I am dead tired | Casual intensifier |
| 疲惫 | píbèi | Exhausted | Formal and written |
| 疲劳 | píláo | Fatigue | Formal, medical or technical |
我很累 versus 我累了
The same 了 pattern that applies to hunger applies here. 我很累 states a degree: I am very tired. 我累了 reports a change of state: I have become tired, I am tired now. When you arrive home after a long day and want to signal that the day has caught up with you, 我累了 is the natural line.
Both are extremely common and neither is more correct. The 很 in 我很累 is not really “very” in the emphatic English sense — it is the standard linker that makes a bare adjective work as a predicate. 我累 would sound abrupt.
累死了 and the 死了 pattern
累死了 (lèi sǐ le) literally means “tired to death” and is the ordinary way to say “I am exhausted”. It belongs to a whole family: 饿死了 (starving), 忙死了 (ridiculously busy), 热死了 (boiling), 冷死了 (freezing). The structure is adjective plus 死了, and it is casual rather than alarming.
Do not use it in formal writing. 非常疲惫 or 非常累 fits a report or an email.
累 has a second reading that changes the meaning
The same character 累 is also read lěi, and in that reading it means to accumulate, pile up or involve. 累积 (lěijī) means to accumulate, 累计 (lěijì) means cumulative, and 连累 (liánlěi) means to implicate someone else. The tone and the meaning are different, and the correct reading depends on the word.
This matters for reading aloud and for looking the character up. A dictionary entry for 累 will list both readings, and the tired sense belongs to the fourth tone lèi.
What it does not mean
累 does not mean bored, and it does not mean lazy. It does not mean exhausted in a medical sense; 疲劳 and 疲惫 are the formal words for that. 困 means sleepy but not tired from work, and it does not mean “trapped” in modern usage even though the classical meaning of 困 was to be surrounded or besieged.
Common mistakes
- Using 累 when you mean sleepy, where 困 is correct.
- Saying 我累 instead of 我很累 or 我累了.
- Reading 累 as lèi in 累积, where it is lěi.
- Using 累死了 in a formal message.
- Assuming 困 means trapped; in everyday modern Chinese it means sleepy.