Square Miles to Square Kilometers Converter
Use this converter to easily convert between Square Miles and Square Kilometers (sq mi to sq km).
How many Square Kilometers equal one Square Mile?
Approximately 2.59 square km equal one square mile, since a mile is defined as 5,280 feet and a foot is defined as 0.3048 meters, then a mile is 1.609344 km and a square mile in km is the area of a square with a side of 1.609344 km. The symbol for square miles is "mi2", often written as "sq mi" while the symbol for square kilometer is "km2", occasionally written as "sq km". Note that writing square miles as m2 or "sq m" could easily lead to confusion with square meters.
Difference between Square Miles and Square Kilometers
Both square kilometers and square miles are units of area of similar magnitude and are both used to measure tracts of land. The square kilometer is a part of the metric system established via the International system of units (SI), while the square mile is a part of the Imperial system of units. "Imperial" is referring to the British Empire in which the unit saw most recent widespread usage.
Miles were used as far back as the Romans (Roman mile equal to 5,000 feet), and different definitions existed in different places and at different times, e.g. English mile, Scot mile, Italian mile. Miles are currently only used in a couple of countries in the world, like the United States and the United Kingdom and so are square miles.
The meter is a much more recent invention / convention with the first definition coming about in 1793 – 1/10,000,000 of the distance between the equator and the North Pole. The meter was redefined last in 1983 as being equal to the distance light travels in 1/299,792,458 seconds in a vacuum. Today, according to the International System of Units (SI), it is the basic measurement unit and the kilometer is simply 1,000 meters. A square kilometer is then the area of a square with a side of 1 kilometer (metre in British English), or 1,000,000 m2.
How to convert Square Miles to Square Kilometers
To convert sq mi to sq km, multiply the measurement in square miles by 2.589988110336 to get the area in square kilometers. Using a calculator is most helpful when accuracy is desired, or the numbers involved are big. Our free online square miles to square kilometers converter should be of assistance in any situation, even offline, given you've loaded the page in your browser and left it open in it.
Square Miles to Square Kilometers conversion example
Sample task: convert 10 mi2 to km2. Solution:
Formula:
mi2 * 2.589988110336 = km2
Calculation:
10 mi2 * 2.59 = 25.899881 km2
End result:
10 mi2 is equal to 25.899881 km2
Square Miles to Square Kilometers conversion table
References
[1] NIST Special Publication 330 (2008) - "The International System of Units (SI)", edited by Barry N.Taylor and Ambler Thompson
[2] International Organization for Standardization (1993). ISO Standards Handbook: Quantities and units (3rd edition). Geneva: ISO. ISBN 92-67-10185-4.
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