The concept of a seven-day week is not native to traditional Chinese calendrical systems but was adopted from the West. However, the way it was implemented reflects a distinct cultural approach. While English names for the days of the week come from Norse and Roman gods (e.g., Thursday from Thor's Day, Saturday from Saturn's Day), the Chinese system is purely numerical and systematic. The days are simply “Star Period One” (Monday), “Star Period Two” (Tuesday), and so on. This logical, numbered system is much easier to learn and reflects a pragmatic approach to language. It avoids mythological or religious references in its standard form, making it universally neutral. This contrasts with the Western system, which requires memorizing unique, historically-derived names for each day. The adoption of the Monday-to-Sunday week is now universal in modern China, with the work week (工作日 gōngzuòrì) running from 星期一 to 星期五 and the weekend (周末 zhōumò) being 星期六 and 星期天.
星期 is fundamental for all daily scheduling. The system is highly regular and easy to master.
You simply add a number from one to six after 星期.
Sunday does not use the number seven. Instead, it has two common names:
To ask “What day of the week is it?”, you use the question word 几 (jǐ), which means “how many” (for small numbers).