Square Kilometer (km²) to Square Millimeter (mm²) Conversion

Definition: A square kilometer (symbol: km²) is a multiple of the square meter, equal to the area of a square with 1 kilometer (1000 meters) on each side. One square kilometer equals 1,000,000 square meters or approximately 0.3861 square miles.

History: Developed as part of the metric system's decimal-based scaling, the square kilometer became particularly useful for geographical measurements. Its adoption grew with the metric system's international acceptance in the 19th and 20th centuries.

Current use: Primarily used to measure large land areas such as cities, national parks, and countries. Commonly appears in geographical surveys, urban planning, and environmental studies. Most world maps and atlases use square kilometers, though some US publications still use square miles.