The acre is an imperial unit of area equal to 43,560 square feet or about 4,047 square meters, predominantly used in the United States, United Kingdom, and former British colonies for land measurement. Real estate listings, farmland boundaries, and suburban lot sizes in these regions are conventionally expressed in acres. One acre is roughly equivalent to 90% of a standard football pitch.

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.