What is the most populous time zone in the world?

China Standard Time is the most populous time zone in the world. China uses UTC+08:00 nationwide, giving more than a billion people the same official clock time.

The arrangement is striking because China is geographically wide enough to span roughly five solar time zones. In 1949, after the founding of the People’s Republic of China, the government standardized the country on a single time system, known domestically as Beijing Time and internationally as China Standard Time. China has not observed daylight saving time since 1991.

The name can cause confusion. China Standard Time is not the same thing as Central Standard Time in North America, and it is two hours ahead of India Standard Time. Hong Kong and Macau also use UTC+08:00, although they retain their own local time authorities. In Xinjiang, some communities additionally use an unofficial local standard called Xinjiang Time, two hours behind Beijing Time.

The country’s single official time creates unusual sunrise and sunset patterns. In far-western Xinjiang, the sun can rise very late by Beijing clocks, while eastern China experiences daylight much earlier.