The square kilometer (km²) equals one million square meters and is used to measure large land areas such as cities, national parks, and countries. Geographic data, urban planning reports, and ecological studies rely on square kilometers as their standard area unit. One square kilometer equals approximately 0.3861 square miles or about 247.1 acres.

The mu (亩) is a traditional Chinese unit of area equal to approximately 666.67 square meters, used extensively in Chinese agriculture, rural land contracts, and property records. Farmland in China is almost always measured in mu, and government policies regarding grain production quotas reference this unit. One mu equals roughly 0.1647 acres or about 7,176 square feet.