Square Miles to Square Kilometers Converter
Enter the area in square miles below to convert it to square kilometers.
Convert Square Miles to Square Kilometers
Enter a value in square miles (mi²) to convert to square kilometers (km²).
Square Mile to Square Kilometer Conversion Table
Table showing various square mile measurements converted to square kilometers. Click any preset value or arrow to load it into the converter.
| Square Miles (mi²) | Square Kilometers (km²) |
|---|---|
| 1 mi² | 2.5899881 km² |
| 2 mi² | 5.1799762 km² |
| 5 mi² | 12.9499406 km² |
| 10 mi² | 25.8998811 km² |
| 15 mi² | 38.8498217 km² |
| 20 mi² | 51.7997622 km² |
| 25 mi² | 64.7497028 km² |
| 30 mi² | 77.6996433 km² |
| 50 mi² | 129.4994055 km² |
| 75 mi² | 194.2491083 km² |
How to Convert Square Miles to Square Kilometers
To convert square miles to square kilometers, multiply the area by the following conversion ratio: 2.5899881 square kilometers/square mile.
Since one square mile is equal to 2.5899881 square kilometers, you can use this simple formula to convert:
The area in square kilometers is equal to the area in square miles multiplied by 2.5899881.
For example, here's how to convert 100 square miles to square kilometers using the formula above.
How Many Square Kilometers Are in a Square Mile?
There are 2.5899881 square kilometers in a square mile, which is why we use this value in the formula above.
Our square mile to square kilometer calculator automatically converts your area measurements with full decimal and scientific precision across US customary, imperial, and SI metric standards.
Square Miles and square kilometers are both units used to measure area. Keep reading to learn more about each unit.
What Is a Square Mile?
A square mile is a unit of area equal to 2,589,988.110336 square meters (m²), the base unit for area. Equal to 640 acres or 2.589988 km². [1]
The square mile is classified as a US customary and imperial unit of area. Square Miles can be abbreviated as mi²; for example, 1 square mile can be written as 1 mi².
When working with square miles (mi²) in formulas or technical specifications, always verify whether your target system uses SI metric, US customary, or British imperial standards.
In practice, square miles (mi²) are widely used across large-scale industrial, bulk, and macro-level area specifications within US customary and imperial workflows, engineering documentation, and technical data sheets.
What Is a Square Kilometer?
A square kilometer is a unit of area equal to 1,000,000 square meters (m²), the base unit for area. Equal to 1,000,000 square meters or 100 hectares. [2]
The square kilometer is classified as an International System of Units (SI) unit of area. Square Kilometers can be abbreviated as km²; for example, 1 square kilometer can be written as 1 km².
When working with square kilometers (km²) in formulas or technical specifications, always verify whether your target system uses SI metric, US customary, or British imperial standards.
In practice, square kilometers (km²) are widely used across large-scale industrial, bulk, and macro-level area specifications within International System of Units (SI) workflows, engineering documentation, and technical data sheets.
When converting area between square miles (mi²) and square kilometers (km²), keep full floating-point precision (1 mi² = 2.5899881 km²; 1 km² = 0.3861022 mi²) during intermediate calculations and round only the final square kilometer figure to match your instrument tolerance.
More Square Mile & Square Kilometer Conversions
Need to calculate in the opposite direction? Use our square kilometers to square miles converter (km² to mi²) to switch your starting unit immediately. You can also explore related tools such as converting square miles to acres, converting square feet to square meters, or converting square meters to square feet.
Convert from Square Miles
Frequently Asked Questions
References
- [1]NIST OWM StandardNIST OWM (SI Units — Length & Area)·Area Metrology Standard — Square Miles (mi²) to Square Kilometers (km²)
- [2]NIST HB 44 SpecificationNIST HB 44 (Acre, Hectare & Land Survey Tables)·Unit Specifications: Square Mile (mi²) & Square Kilometer (km²)
- [3]NIST SP 811 ReferenceNIST SP 811 (NIST SP 811 App. B.9 (Area))·Conversion Factors & Mathematical Basis (mi² to km²)