Square Miles to Square Kilometers Converter

Why the factor isn't just 1.60934

Squaring a linear conversion factor squares the unit too: since 1 mile = 1.60934 km, 1 square mile = 1.60934² = 2.58998811 square kilometers. Area conversions between mile-based and kilometer-based units always use the squared factor, not the linear one — a common source of error when converting area by hand.

Worked example

Enter 10 square miles and the tool returns 25.899881 square kilometers (10 × 2.58998811 = 25.8998811, displayed to six decimal places). For 1 square mile exactly, the result is 2.598988 sq km.

Reference areas

This tool displays six decimal places rather than the two used by most linear converters on this site, because area conversion factors compound rounding error faster — a small error in the linear factor becomes roughly double that percentage error once squared.