‘公斤’ is the standard Mandarin term for ‘kilogram’, the base unit of mass in the metric system. It literally combines 公 (gōng), meaning ‘public’ or ‘standard’, and 斤 (jīn), a traditional Chinese unit of weight roughly equal to 500 grams. Together, 公斤 signifies the ‘standard jīn’ — that is, the officially adopted metric version, equivalent to 1,000 grams (or 2 traditional shì jīn). This term is universally used in mainland China, scientific contexts, commerce, nutrition labels, and official measurements.

Unlike the traditional 斤 (which varies regionally but is standardized as 500 g in modern China), 公斤 avoids ambiguity and aligns with international standards. You’ll encounter it frequently in supermarkets, recipes, medical dosages, luggage weight limits, and fitness tracking. It’s neutral in register — appropriate for both formal reports and casual conversation — and always functions as a countable noun, typically preceded by a number or measure word like ‘一’ or ‘几’.