Convert Square Kilometer to Square Mile
Convert square kilometers to square miles instantly. 1 square kilometer = 0.3861021585 square mile — use the live calculator, the exact formula, a conversion table and worked examples. Also check the Square Mile to Square Kilometer converter for the reverse conversion.
Units explained
Square Kilometer
A square kilometer is a metric unit of area equal to 1,000,000 m² (one million square meters), or 100 hectares. It is used for measuring large land areas, regional geography, and country-scale statistics.
Derived by squaring the kilometer (1000 m). The kilo- prefix comes from the Greek 'chilioi' (thousand).
Square kilometers express the area of cities, districts, lakes, forests, and entire countries. India's total area is approximately 3,287,263 km². 1 km² equals 100 hectares or about 247.105 acres.
Kilometer has been part of the metric system since 1795.
Square Mile
A square mile is an imperial unit of area equal to exactly 2,589,988.110336 m². It is used for measuring large land areas in the United States and the United Kingdom.
Derived by squaring the statute mile (5,280 feet). The mile was standardized via the 1959 International Yard and Pound Agreement.
Square miles are used for US and UK regional geography (county areas, lake sizes, large parks), national statistics, and military range descriptions. 1 mi² = 640 acres = 2.589988 km².
Mile dates to Roman antiquity; modern exact value standardized in 1959.
Square Kilometer to Square Mile conversion formula
The relationship between square kilometers and square miles:
To convert square kilometers to square miles, multiply the value in square kilometers by 0.3861021585. To reverse, multiply square miles by 2.5899881103.
How to use this converter
Type a value into the calculator. The result in square miles updates as you type. Tap a quick value, copy the result with one click, or use the swap arrow to jump straight to the Square Mile to Square Kilometer converter for the reverse direction.
Step-by-step: convert square kilometers to square miles
- Write down the value in square kilometers (km²).
- Multiply that value by the factor 0.3861021585.
- The product is the equivalent value in square miles (mi²).
- To reverse, multiply the square mile value by 2.5899881103.
Worked examples
Example 1 — Convert 1 km² to mi²:
1 × 0.3861021585 = 0.3861021585 mi²
Example 2 — Convert 100 km² to mi²:
100 × 0.3861021585 = 38.6102158542 mi²
Square Kilometer to Square Mile conversion table
Standard reference values for converting square kilometers to square miles:
| Square Kilometer [km²] | Square Mile [mi²] |
|---|---|
| 0.01 | 0.0038610216 |
| 0.1 | 0.0386102159 |
| 1 | 0.3861021585 |
| 2 | 0.7722043171 |
| 3 | 1.1583064756 |
| 4 | 1.5444086342 |
| 5 | 1.9305107927 |
| 10 | 3.8610215854 |
| 20 | 7.7220431708 |
| 30 | 11.5830647563 |
| 40 | 15.4440863417 |
| 50 | 19.3051079271 |
| 100 | 38.6102158542 |
| 500 | 193.0510792712 |
| 1000 | 386.1021585424 |
Frequently asked questions
How many square miles is 1 square kilometer?
How do I convert square kilometers to square miles?
How do I convert square miles back to square kilometers?
How many square miles is 100 square kilometers?
Popular area unit conversions
Convert Square Kilometer to other area units
Show all Square Kilometer conversions
Metric / SI (15 units)
Imperial / US Customary (15 units)
US Survey (5 units)
Indian Subcontinent (16 units)
Other Regional (10 units)
Scientific / Physics (5 units)
Sources & references
Conversion factor (1 km² = 0.3861021585 mi²) verified against the following authoritative sources:
- BIPM — The International System of Units (SI Brochure 9th ed.)
Official BIPM publication defining the seven SI base units (including the meter) and the rules for their use. The global authority on units of measurement.
- NIST — Guide to the SI
US National Institute of Standards and Technology reference covering the SI base and derived units with definitions and usage rules for US technical practice.
- NIST Special Publication 811 — Guide for the Use of the International System of Units
Detailed NIST guide covering exact conversion factors between SI and US customary units along with formatting and rounding conventions.
- NIST — Refinement of values for the yard and pound (Federal Register 1959)
The treaty (signed by US
- International Hydrographic Organization — Resolution on the Nautical Mile
International authority that standardised the nautical mile at exactly 1852 m in 1929 — the value adopted worldwide for sea and air navigation.