‘啥时候’ is an informal, colloquial contraction of ‘什么时候’ (shén me shí hou), meaning ‘when’. It’s widely used in spoken Mandarin, especially in northern China and in casual conversation. The character 啥 is a dialectal variant of 什么 (what), while 时 and 候 together mean ‘time’ or ‘moment’—so literally, ‘what time’. Unlike the standard form, ‘啥时候’ carries a relaxed, conversational tone and is rarely appropriate in formal writing or speeches.

This expression functions as an adverbial interrogative phrase, typically placed at the beginning or end of a question to ask about time. It can refer to past, present, or future events, and often appears with verbs like 来 (come), 走 (leave), or 吃饭 (eat). Because it’s informal, learners should avoid using it in academic, professional, or official contexts—opt instead for ‘什么时候’ in those situations.