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 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.