Square Mile to Square Kilometer Converter
Area · unit-converter
Convert Square Mile to Square Kilometer with a fixed input and output unit, step-by-step formula line, and reference tables. All calculations use square-meter-based definitions (international feet / yard standards, acre, hectare, and regional units like pyeong/tsubo).
Calculator
From: Square Mile (mi2)
To: Square Kilometer (km2)
About Square Mile
The square mile is an imperial and US customary unit of area equal to the area of a square one statute mile on a side. It is common for large land parcels and geography in the US and UK.
About Square Kilometer
The square kilometer is a metric unit equal to one million square meters. It is standard for city sizes, large properties, and regional planning in metric countries.
How to convert square miles to square kilometers
1 square mile is equal to 2.589988110336 square kilometer:
1 mi2 = (2589988.110336 m² ÷ 1000000 m²) km2 = 2.589988110336 km2
Each square mile is defined as 2589988.110336 m² and each square kilometer as 1000000 m², so one mi2 equals 2589988.110336 ÷ 1000000 km2 = 2.589988110336 km2.
Let a(mi2) be the numeric value of the same area measured in Square Mile (mi2), and a(km2) the value in Square Kilometer (km2). Then:
a(km2) = a(mi2) × (2589988.110336 / 1000000)
Equivalently, divide by how many mi2 fit into one km2 (m² per km2 divided by m² per mi2):
a(km2) = a(mi2) ÷ 0.38610215854245
Or: square kilometer = square mile ÷ 0.38610215854245
Examples
Example #1: Convert 20 mi2 to square kilometer
20 mi2 = 20 mi2 × (2589988.110336/1000000) km2 = 51.7997622067 km2
20 mi2 = 20 mi2 ÷ 0.38610215854245 = 51.7997622067 km2
Example #2: Convert 50 mi2 to square kilometer
50 mi2 = 50 mi2 × (2589988.110336/1000000) km2 = 129.499405517 km2
50 mi2 = 50 mi2 ÷ 0.38610215854245 = 129.499405517 km2
Summary
To convert Square Mile to Square Kilometer, multiply the value in mi2 by the ratio of square meters per mi2 divided by square meters per km2. Equivalently: value_km2 = value_mi2 × (2589988.110336 / 1000000). Numerically, 1 mi2 equals 2.5899881103360003 km2.
Relationship context
You are converting between US customary / imperial (Square Miles) and metric (SI) (Square Kilometers). Metric area is decimal from the square meter; US/imperial units use feet, yards, miles, and acres tied to international feet (0.3048 m) and related definitions. The numeric factor used here is 2.589988e+0.
Conversion tables
| Square Mile (mi2) | Square Kilometer (km2) |
|---|---|
| 0.1 | 0.258998811 |
| 1 | 2.5899881103 |
| 2 | 5.1799762207 |
| 3 | 7.769964331 |
| 4 | 10.3599524413 |
| 5 | 12.9499405517 |
| 6 | 15.539928662 |
| 7 | 18.1299167724 |
| 8 | 20.7199048827 |
| 9 | 23.309892993 |
| Square Mile (mi2) | Square Kilometer (km2) |
|---|---|
| 10 | 25.8998811034 |
| 20 | 51.7997622067 |
| 30 | 77.6996433101 |
| 40 | 103.599524413 |
| 50 | 129.499405517 |
| 60 | 155.39928662 |
| 70 | 181.299167724 |
| 80 | 207.199048827 |
| 90 | 233.09892993 |
| 100 | 258.998811034 |