Authoritative definitions of the International System of Units and SI prefixes.
Dedicated unit pair
Square miles to Square kilometres
Convert mi² to km² instantly, then review the formula, assumptions, and rounding guidance.
AreaInstant result
Decimals
Formula result = input × 2589988.110336 ÷ 1000000. 1 mi² = 2.59 km²
Common examples
One value, several units
Square metres2,589,988.1103 m²
Square kilometres2.59 km²
Square centimetres25,899,881,103.36 cm²
Hectares258.9988 ha
Acres640 ac
Square feet27,878,400 ft²
Square inches4,014,489,600 in²
Conversion table
| mi² | km² |
|---|---|
| 1 mi² | 2.59 km² |
| 2 mi² | 5.18 km² |
| 5 mi² | 12.9499 km² |
| 10 mi² | 25.8999 km² |
| 25 mi² | 64.7497 km² |
| 50 mi² | 129.4994 km² |
| 100 mi² | 258.9988 km² |
Conversion chart
1 mi²2.59 km²
5 mi²12.9499 km²
10 mi²25.8999 km²
25 mi²64.7497 km²
50 mi²129.4994 km²
Worked example
1 hectare equals 10,000 square metres.
Unit definition
Square miles (mi²) One square miles equals 2,589,988.11034 square metre.
Unit history
Square miles is represented here using its modern SI definition or an internationally accepted relationship to an SI base unit.
Step by step
1. Parse the value, including fractions.
2. Convert mi² to square metre.
3. Convert the base value to km² and apply your display precision.
Understand the result before using it
Square miles to Square kilometres converts a value measured in Square miles (mi²) into the equivalent value in Square kilometres (km²). The numerical value changes because the size and definition of the selected unit changes; the underlying quantity does not.
Calculated result
The conversion follows the displayed unit relationship. Display rounding can hide additional digits, and measured inputs cannot become more accurate merely by changing units.
Formula, assumptions, and example
Formula
result = input × 2589988.110336 ÷ 1000000
Assumptions
- Square miles and Square kilometres represent the same area quantity.
- The input is expressed in mi²; the output is expressed in km².
- The unit definitions and conventional relationship shown on this page apply.
Worked example
1 mi² = 2.58998811034 km². For another value, apply the same relationship and round only to the precision your source measurement supports.
When to use it
Good uses
- Read a mi² measurement in a document that expects km².
- Compare a square miles value with a value reported in square kilometres.
- Check the mi²-to-km² arithmetic before copying the result into another calculation.
Limitations
Common mistakes to avoid
- Do not apply a linear length factor directly to area; the length factor must be squared.
- Round the output to a precision justified by the original measurement.
- Verify safety-critical, regulated, laboratory, and contractual conversions against the controlling standard.
Sources and further reading
These references explain the underlying standards or provide authoritative context. Your own contract, institution, clinician, product documentation, local code, or governing standard may be the controlling source.
Guidance on unit names, symbols, conversions, and numerical presentation.
Questions about this calculation
How do I convert Square miles to Square kilometres?
result = input × 2589988.110336 ÷ 1000000 Using the displayed relationship, 1 mi² equals 2.58998811034 km².
How many Square kilometres are in one Square miles?
One Square miles is 2.58998811034 Square kilometres. The displayed digits may be rounded.
Can I reverse the mi² to km² conversion?
Yes. Swap the source and target units in the converter. The reverse relationship converts km² back to mi².
Is the Square miles to Square kilometres result exact?
The conversion follows the displayed unit relationship. Display rounding can hide additional digits, and measured inputs cannot become more accurate merely by changing units.