Square Miles to Square Kilometers Converter

Use this converter to easily convert between Square Miles and Square Kilometers (sq mi to sq km).

mi2
km2
Share converter:

Embed this tool!
get code

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

sq mi to sq km conversion table
sq mi sq km
1 sq mi 2.589988 sq km
2 sq mi 5.179976 sq km
3 sq mi 7.769964 sq km
4 sq mi 10.359952 sq km
5 sq mi 12.949941 sq km
6 sq mi 15.539929 sq km
7 sq mi 18.129917 sq km
8 sq mi 20.719905 sq km
9 sq mi 23.309893 sq km
10 sq mi 25.899881 sq km
20 sq mi 51.799762 sq km
30 sq mi 77.699643 sq km
40 sq mi 103.599524 sq km
50 sq mi 129.499406 sq km
60 sq mi 155.399287 sq km
70 sq mi 181.299168 sq km
80 sq mi 207.199049 sq km
90 sq mi 233.098930 sq km
100 sq mi 258.998811 sq km
200 sq mi 517.997622 sq km
300 sq mi 776.996433 sq km
400 sq mi 1,035.995244 sq km
500 sq mi 1,294.994055 sq km
600 sq mi 1,553.992866 sq km
700 sq mi 1,812.991677 sq km
800 sq mi 2,071.990488 sq km
900 sq mi 2,330.989299 sq km
1,000 sq mi 2,589.988110 sq km

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.

Cite this converter & page

If you'd like to cite this online converter resource and information as provided on the page, you can use the following citation:
Georgiev G.Z., "Square Miles to Square Kilometers Converter", [online] Available at: https://www.gigacalculator.com/converters/convert-sqmi-to-square-km-miles.php URL [Accessed Date: 18 Sep, 2019].