Zhangjiakou is a prefecture-level city located in northwestern Hebei province in northern China. It shares borders with Beijing to the southeast, Inner Mongolia to the north and west, and Shanxi to the southwest. The city is also known by the name Kalgan.
The region covers an area of 36,861.56 square kilometres and is divided into 17 counties and districts. As of 2020, the population was 4,118,908 inhabitants. The built-up area consists of the Qiaoxi, Qiaodong, Chongli, Xuanhua, and Xiahuayuan districts, which are largely conurbated.