半斤 (bàn jīn) literally means 'half a catty' — a traditional Chinese unit of weight equal to 500 grams divided in half, i.e., 250 grams. The character 半 means 'half', and 斤 is an ancient weight unit still used informally in markets and daily speech, especially in mainland China and Taiwan. Though the metric system is official, many people, particularly older generations or vendors in wet markets, still refer to produce, meat, or herbs by 斤 and its fractions like 半斤.

This term appears frequently in shopping contexts, recipes, and idiomatic expressions — most famously in the idiom 半斤八两 (bàn jīn bā liǎng), meaning 'six of one, half-dozen of the other', implying two things are essentially equal in value or quality. While not used for precise scientific measurement today, 半斤 remains culturally embedded and widely understood in everyday conversation about quantity and weight.