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Free Square Kilometers to Square Miles Converter

Square kilometers and square miles both measure large geographic regions—cities, lakes, forests, and countries. This converter helps you compare land masses and understand regional statistics when crossing metric-versus-customary borders in cartography, climatology, and geopolitical analysis.

1 km² = 0.3861 mi²

Pick any units and edit either box — it converts instantly in your browser.

Quick answer

1 square kilometer equals 0.3861 square miles. Multiply square kilometers by 0.3861 to get square miles, or divide square miles by 0.3861 for kilometers.

Formula & method

square miles = square kilometers × 0.3861021585
  • km² — value in square kilometers
  • mi² — result in square miles
  • 0.3861021585 — exact conversion factor (1 km² = 0.3861021585 mi²)

To convert back, divide by 0.3861021585 (1 mi² = 2.589988 km²).

Square Kilometers to Square Miles — common values

Square Kilometers (km²)Square Miles (mi²)
1 km²0.3861 mi²
2 km²0.7722 mi²
5 km²1.9305 mi²
10 km²3.861 mi²
50 km²19.3051 mi²
100 km²38.6102 mi²
500 km²193.0511 mi²
1,000 km²386.1022 mi²

Examples

Example 1: Small urban neighborhood or town
Input
1 km²
Result
0.3861 mi²
Why
A local area roughly the size of a downtown core, small village, or university campus.
Example 2: City district or suburb
Input
10 km²
Result
3.861 mi²
Why
A significant municipal district within a major metropolitan area, or a small rural county.
Example 3: Major metropolitan area
Input
100 km²
Result
38.6102 mi²
Why
The urbanized footprint of cities like Denver or Portland, or a large regional forest or park system.
Example 4: Large country or region
Input
1,000 km²
Result
386.1022 mi²
Why
A country like Iceland or a US state like Rhode Island; global lake or geographic features.

Common mistakes

  • Rounding too early. Multiply by the full factor (0.3861021585) first, then round only the final square miles value.
  • Converting the wrong way. This page goes Square Kilometers → Square Miles; to go back, divide by 0.3861021585.

Frequently asked questions

How many square miles is 1 square kilometer?

Exactly 0.3861021585 square miles. This ratio comes from 1 km = 0.6214 miles, so 1 km² = (0.6214)² mi².

Why do US geographic sources use square miles instead of square kilometers?

The US retained the customary system; most other nations adopted metric. US maps, weather forecasts, and geographic databases all use square miles as the standard unit for area.

What's the area of my country or region in square kilometers vs. square miles?

Example: the UK is ~243,000 km² or ~93,800 mi². Use this converter to compare any region listed in one system to understand it in the other.

How do square kilometers relate to hectares?

100 hectares = 1 square kilometer. If you're converting agricultural land from hectares, first convert to sq km, then use this tool to get square miles.

Is this conversion the same as the foot-to-meter conversion?

Yes—both are based on the SI definition. 1 km = 1000 m, 1 mile = 1.60934 km, so 1 mi² = 2.58999 km². The reverse factor (km² to mi²) is 0.3861.

How is geographic area used in climate and environmental reports?

International climate data (IPCC, UN) and most scientific publications use square kilometers. US environmental agencies use square miles. Journalists and public communicators often convert for their audience.

Sources & references

External references open in a new tab. We are independent and not affiliated with these organizations.

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Last updated: How we calculateReport a correctionDisclaimer

Provided “as is” for general information only — results may be inaccurate, so verify before you rely on them. No warranty; use at your own risk.

Built and reviewed by HIFreeTools against the formula shown above and any authoritative references cited on this page. See our methodology and editorial standards.

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