Square miles to Square kilometers (mi² to km²)

How to convert square miles to square kilometers

To convert square miles to square kilometers, multiply the value in mi² by 2.58999 — km² = mi² × 2.58999. The calculator above does this instantly for any value, in both directions — use Swap units to reverse it.

Square miles to Square kilometers conversion table

Related conversions

Need the opposite direction? Square kilometers to Square miles. Every area pair lives on the area converter page, and the full unit converter covers six other categories.

Convert square miles to other units

Popular area conversions

Common mistakes to avoid

• Mixing up ounces. The Weight category uses the ounce (oz), a unit of mass (28.3495 g). The Volume category uses the US fluid ounce (fl oz), a unit of capacity (29.5735 mL). One fluid ounce of water weighs about 1.04 oz, not exactly 1 oz, so always confirm which category you are in before converting.
• Confusing bits and bytes. File sizes are measured in bytes, network speeds in bits. In Data storage, 1 byte equals 8 bits, so a 100 Mbit per second connection transfers at most 12.5 megabytes per second.
• Assuming imperial gallons. Every volume unit here is US customary: 1 US gallon is 3.785 liters. A UK imperial gallon is 4.546 liters, roughly 20 percent larger, so results will not match UK fuel economy figures.

A quick accuracy check

Want to sanity-check any converter? Convert -40 from Celsius to Fahrenheit: the result must be exactly -40, the only temperature where the two scales meet. Then convert 0 Kelvin to Celsius: you should get -273.15, absolute zero. A converter that handles both edge cases correctly has sound temperature formulas, and this one does.

Frequently asked questions