Convert square miles to square km

One square mile equals 2.589988 square kilometers. To convert any number of square miles to square kilometers, multiply by 2.58998811.

The converter above works in both directions and updates as you type. Below you will find the formula, a worked example and a reference table of common values.

Area conversions carry a trap that catches people who are perfectly comfortable with length: the factor is squared. There are 3.28 feet in a metre but 10.76 square feet in a square metre, and using the linear factor is the most common error in property arithmetic. Beyond that, land is measured in whatever the local convention prescribes — acres, hectares, and across South Asia bigha, katha and gaj — so the same plot is routinely described in two units that need reconciling.

square miles to square km formula

To go the other way, use square mile = square kilometer ÷ 2.58998811.

About these units

A square mile is 640 acres, which is why a US Public Land Survey section — one square mile — divides so neatly into quarter-sections of 160 acres.

A square kilometre is 100 hectares, or about 247 acres. It is the standard unit for the area of a town, a lake or a national park.

Square Mile is also written square miles, sq mi and mi2. Square Kilometer is also written square kilometre, sq km and km2.

Sources

1. National Bureau of Standards, "Refinement of Values for the Yard and the Pound", Federal Register, 1 July 1959 — the international yard as exactly 0.9144 m and the avoirdupois pound as exactly 0.45359237 kg.