Square Kilometer (km²) - Unit Information & Conversion

Quick Answer

What is a square kilometer? A square kilometer (km²) is the area of a square with sides exactly 1 kilometer long. It equals 1,000,000 square meters, 100 hectares, or about 0.386 square miles (247 acres). Used for measuring countries, cities, and large geographical areas. Use our area converter to convert km² to sq mi, hectares, acres, and more instantly.

Quick Comparison Table

Square Kilometers	Square Miles	Hectares	Common Example	Convert Now
0.1 km²	0.04 mi²	10 ha	Large park or farm	Convert →
1 km²	0.39 mi²	100 ha	Small neighborhood	Convert →
10 km²	3.86 mi²	1,000 ha	Small town	Convert →
100 km²	38.6 mi²	10,000 ha	Medium city	Convert →
1,000 km²	386 mi²	100,000 ha	Large city	Convert →
10,000 km²	3,861 mi²	1,000,000 ha	Small country/large region	Convert →
100,000 km²	38,610 mi²	10,000,000 ha	Large country/state	Convert →

Need a different conversion? Try our area converter for all area units.

Definition

The Square Kilometer (symbol: km² or sq km) is a multiple of the square meter (m²), the base unit of area in the International System of Units (SI). It represents the area of a square whose sides measure exactly one kilometer (km) in length.

Key relationships:

• 1 km² = 1 kilometer × 1 kilometer
• 1 km = 1,000 meters (m)
• Therefore, 1 km² = (1,000 m) × (1,000 m) = 1,000,000 square meters (m²)
• 1 km² = 100 hectares (ha) (since 1 hectare = 10,000 m²)

In terms of imperial/US customary units:

• 1 km² ≈ 0.3861 square miles (mi²) - Convert km² to mi²
• 1 km² ≈ 247.1 acres (ac) - Convert km² to acres
• 1 km² ≈ 10,763,910 square feet (ft²)

Visual perspective:

• 1 km² = 100 football fields (American)
• 1 km² = ~150 soccer fields
• 1 km² = Walking distance of about 1 km × 1 km
• 10 km² = Typical small town
• 100 km² = Medium-sized city
• 1,000 km² = Large metropolitan area

Convert between area units: Square kilometer converter

History

• Origin: The square kilometer is derived directly from the kilometer, a unit of length introduced as part of the metric system, which was developed in France during the late 18th century (1790s).

• Metric System Adoption: The metric system, including the meter and its multiples like the kilometer, was created to provide a standardized, decimal-based system of measurement to replace the chaotic local units of pre-revolutionary France.

• Natural Evolution: As nations began adopting the metric system throughout the 19th and 20th centuries, the square kilometer naturally became the standard unit for expressing large geographical areas - countries, regions, cities, lakes, and forests.

• International Standardization: The need for a universal unit for geographical measurement became critical as:

  • World maps and atlases were standardized
  • International treaties needed land area specifications
  • Global trade required consistent land measurements
  • Scientific exploration needed standard area units

• SI Standard: The International System of Units (SI), formally established in 1960, confirmed the square meter (m²) as the base unit of area. The square kilometer is a widely accepted and commonly used multiple of this base unit, consistent with SI prefixes (kilo = 1,000).

• Global Usage Today: The square kilometer is now the predominant unit used worldwide for measuring:

  • Land area of countries and territories
  • Surface area of continents and islands
  • Size of administrative divisions (states, provinces, counties)
  • Area of cities and metropolitan regions
  • Size of bodies of water (lakes, seas)
  • Extent of forests, deserts, and ecosystems
  • National parks and protected areas

• Note on spelling: "Kilometer" (US) and "kilometre" (UK/International) both produce "square kilometer" and "square kilometre" respectively, both referring to the same unit: 1,000,000 m².

Real-World Examples

Countries by Area

Small Countries (Under 1,000 km²):

• Vatican City: 0.44 km² (smallest country)
• Monaco: 2.02 km²
• San Marino: 61 km²
• Liechtenstein: 160 km²
• Malta: 316 km²
• Maldives: 300 km²
• Singapore: 728 km²

Medium Countries (1,000 - 100,000 km²):

• Luxembourg: 2,586 km²
• Qatar: 11,586 km²
• Jamaica: 10,991 km²
• Lebanon: 10,452 km²
• Israel: 22,072 km²
• Belgium: 30,528 km²
• Netherlands: 41,543 km²
• Switzerland: 41,285 km²
• Denmark: 42,933 km²

Large Countries (100,000 - 1,000,000 km²):

• Iceland: 103,000 km²
• Guatemala: 108,889 km²
• United Kingdom: 242,495 km²
• Germany: 357,022 km²
• Japan: 377,975 km²
• Norway: 323,802 km²
• Poland: 312,696 km²
• Italy: 301,340 km²
• Philippines: 300,000 km²
• New Zealand: 268,021 km²
• Ecuador: 283,561 km²

Very Large Countries (1,000,000+ km²):

• Greenland: 2,166,086 km² (largest island)
• Saudi Arabia: 2,149,690 km²
• Mexico: 1,964,375 km²
• Indonesia: 1,904,569 km²
• Libya: 1,759,540 km²
• Iran: 1,648,195 km²
• Mongolia: 1,564,110 km²
• Peru: 1,285,216 km²
• Chad: 1,284,000 km²
• Niger: 1,267,000 km²

Top 10 Largest Countries:

1. Russia: 17,098,242 km² (largest country)
2. Canada: 9,984,670 km²
3. USA: 9,833,517 km²
4. China: 9,596,961 km²
5. Brazil: 8,515,767 km²
6. Australia: 7,692,024 km²
7. India: 3,287,263 km²
8. Argentina: 2,780,400 km²
9. Kazakhstan: 2,724,900 km²
10. Algeria: 2,381,741 km²

Compare country sizes: km² to mi²

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US States by Area

Largest States:

• Alaska: 1,723,337 km² (663,268 mi²) - largest US state
• Texas: 695,662 km² (268,596 mi²)
• California: 423,967 km² (163,696 mi²)
• Montana: 380,831 km² (147,040 mi²)
• New Mexico: 314,917 km² (121,590 mi²)
• Arizona: 295,234 km² (113,990 mi²)
• Nevada: 286,380 km² (110,572 mi²)
• Colorado: 269,601 km² (104,094 mi²)
• Oregon: 254,799 km² (98,379 mi²)
• Wyoming: 253,335 km² (97,813 mi²)

Smallest States:

• Rhode Island: 3,140 km² (1,212 mi²) - smallest US state
• Delaware: 6,446 km² (2,489 mi²)
• Connecticut: 14,357 km² (5,543 mi²)
• New Jersey: 22,591 km² (8,723 mi²)
• New Hampshire: 24,214 km² (9,349 mi²)

Medium States:

• Florida: 170,312 km² (65,758 mi²)
• New York: 141,297 km² (54,555 mi²)
• Michigan: 250,487 km² (96,714 mi²)
• Pennsylvania: 119,280 km² (46,054 mi²)
• Ohio: 116,098 km² (44,826 mi²)

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Major Cities by Area

Largest Cities by Land Area:

• Tokyo, Japan: 2,194 km²
• New York City, USA: 1,214 km²
• Los Angeles, USA: 1,302 km²
• London, UK: 1,572 km²
• Paris, France: 105 km² (city proper), 17,174 km² (metro area)
• Moscow, Russia: 2,511 km²
• Beijing, China: 16,411 km²
• Shanghai, China: 6,341 km²
• Mexico City, Mexico: 1,485 km²
• São Paulo, Brazil: 1,521 km²
• Sydney, Australia: 12,368 km² (metro area)
• Chicago, USA: 606 km²
• Houston, USA: 1,651 km²
• Phoenix, USA: 1,344 km²
• Rome, Italy: 1,285 km²

Note: City areas vary based on official boundaries (city proper vs metro area vs urban area).

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Bodies of Water

Lakes:

• Caspian Sea: 371,000 km² (largest lake)
• Lake Superior: 82,100 km²
• Lake Victoria: 68,800 km²
• Lake Huron: 59,600 km²
• Lake Michigan: 58,000 km²
• Lake Tanganyika: 32,900 km²
• Lake Baikal: 31,722 km²
• Great Bear Lake: 31,153 km²
• Lake Malawi: 29,600 km²
• Great Slave Lake: 28,568 km²
• Lake Erie: 25,700 km²
• Lake Ontario: 19,000 km²

Seas:

• Mediterranean Sea: 2,500,000 km²
• Caribbean Sea: 2,754,000 km²
• South China Sea: 3,500,000 km²
• Bering Sea: 2,000,000 km²
• Sea of Okhotsk: 1,583,000 km²
• Black Sea: 436,400 km²
• Red Sea: 438,000 km²
• Baltic Sea: 377,000 km²

Oceans (for reference):

• Pacific Ocean: 165,200,000 km²
• Atlantic Ocean: 106,460,000 km²
• Indian Ocean: 70,560,000 km²
• Southern Ocean: 20,327,000 km²
• Arctic Ocean: 14,060,000 km²

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Islands

Largest Islands:

• Greenland: 2,166,086 km² (largest island)
• New Guinea: 785,753 km²
• Borneo: 748,168 km²
• Madagascar: 587,041 km²
• Baffin Island: 507,451 km²
• Sumatra: 443,066 km²
• Honshu (Japan): 227,960 km²
• Victoria Island: 217,291 km²
• Great Britain: 209,331 km²
• Ellesmere Island: 196,236 km²

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National Parks and Protected Areas

Large National Parks:

• Northeast Greenland National Park: 972,000 km² (largest protected area)
• Yellowstone National Park (USA): 8,983 km²
• Yosemite National Park (USA): 3,083 km²
• Grand Canyon National Park (USA): 4,926 km²
• Kruger National Park (South Africa): 19,485 km²
• Serengeti National Park (Tanzania): 14,763 km²
• Great Barrier Reef Marine Park (Australia): 344,400 km²
• Amazon Rainforest (total): ~5,500,000 km²

Common Uses

The square kilometer is the international standard for measuring large-scale areas:

Geography and Cartography

The standard unit for stating land or surface area of countries, continents, large islands, administrative divisions (states, provinces), and major cities.

Geographic Applications:

• Country and territory sizes
• Continental land masses
• Island and archipelago areas
• Administrative boundaries
• Political divisions
• City and metropolitan areas

Why it's universal:

• Standardized for international comparison
• Used in atlases, maps, and geographic databases
• Required for official government statistics
• Essential for treaties and agreements

Convert for international comparisons

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Demography

Essential for calculating population density, typically expressed as inhabitants per square kilometer (people/km²). This is the international standard for comparing population distribution.

Population Density Uses:

• Comparing urban vs rural population spread
• Planning infrastructure needs
• Resource allocation per capita
• Understanding settlement patterns
• Environmental impact assessment

Formula: Population Density = Total Population ÷ Area (km²)

Example: Japan has 333 people/km², while Canada has only 4 people/km²

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Environmental Science

Measuring the extent of large ecosystems, national parks, conservation areas, watersheds, ice sheets, deforestation, and environmental impacts.

Environmental Applications:

• Forest monitoring: Amazon = 5.5 million km²
• Deforestation tracking: Loss measured in km²/year
• Protected areas: Park sizes, marine reserves
• Ice sheet coverage: Antarctic ice = 14 million km²
• Disaster areas: Flood extent, wildfire spread, oil spill coverage
• Habitat mapping: Species range and distribution

Climate Research:

• Sea ice extent (measured seasonally in km²)
• Glacier coverage changes
• Desert expansion/contraction
• Vegetation cover changes

Use our square kilometer converter for environmental calculations.

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Urban Planning and Land Management

Quantifying large zones, districts, or total city area in regional planning, metropolitan development, and land use management.

Urban Applications:

• City boundaries and total area
• Metropolitan area extent
• Urban sprawl measurement
• Zoning district sizes
• Green space allocation
• Development planning

Regional Planning:

• Transportation networks
• Utility coverage areas
• Emergency service zones
• School district boundaries
• Municipal service areas

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Geology and Planetary Science

Measuring the surface area of large geological formations or the surface areas of planets, moons, and asteroids.

Geological Features:

• Volcanic fields
• Impact craters
• Lava flow areas
• Tectonic plate coverage
• Mineral deposit areas

Planetary Measurements:

• Earth surface: 510 million km²
• Mars surface: 145 million km²
• Moon surface: 38 million km²
• Crater sizes on planets/moons

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Military and Logistics

Defining large operational areas, zones, and territories for defense, operations planning, and strategic analysis.

Military Applications:

• Theater of operations
• Exclusion zones
• Patrol areas
• Training grounds
• Strategic territories

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Real Estate and Property (Large Scale)

While hectares or acres are more common for individual properties, square kilometers are used for:

• Very large land holdings (ranches, estates)
• Land development projects
• Agricultural regions
• Forestry concessions
• Mining leases

Example: A large cattle ranch might be 100-500 km²

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Agriculture (Regional Scale)

While individual farms use hectares, agricultural regions and total crop areas are measured in square kilometers:

• Total agricultural land per country
• Grain belt regions
• Wine regions
• Crop suitability zones
• Irrigation coverage areas

Example: Corn Belt in USA covers approximately 500,000 km²

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International Comparisons

Essential for comparing regions, countries, and geographic features across borders and continents.

Comparison Uses:

• "Country X is about the size of State Y"
• "This forest is larger than Country Z"
• "The disaster area equals 10 times the size of City A"

Common Comparisons:

• Singapore (728 km²) is smaller than New York City (1,214 km²)
• United Kingdom (242,495 km²) is about the same size as Oregon (254,799 km²)
• Australia (7.7 million km²) is about the same size as the contiguous USA (8.1 million km²)

Convert for comparisons: km² to square miles | km² to acres

Common Conversion Mistakes to Avoid

❌ Mistake #1: Forgetting to Square the Conversion Factor

• Wrong: 1 km = 0.621 miles, so 1 km² = 0.621 mi²
• Correct: 1 km² = (0.621)² = 0.386 mi²
• Why: Area conversion requires squaring the linear conversion
• Example: 10 km² = 3.86 mi², NOT 6.21 mi²
• Fix: Always use our km² to mi² converter

❌ Mistake #2: Confusing km² with Hectares

• Wrong: 1 km² = 1,000 hectares
• Correct: 1 km² = 100 hectares (not 1,000!)
• Remember: 1 hectare = 10,000 m², so 100 hectares = 1,000,000 m² = 1 km²
• Example: 5 km² = 500 hectares, NOT 5,000 hectares
• Tool: km² to hectare converter

❌ Mistake #3: Wrong Square Meter Conversion

• Wrong: 1 km² = 1,000 m² (thinking linearly)
• Correct: 1 km² = 1,000,000 m² (1,000 × 1,000)
• Remember: 1 km = 1,000 m, so 1 km² = 1,000 m × 1,000 m = 1,000,000 m²
• Example: 2.5 km² = 2,500,000 m², NOT 2,500 m²
• Convert: km² to m² converter

❌ Mistake #4: Decimal Point Errors with Acres

• Wrong: 1 km² = 2.47 acres
• Correct: 1 km² = 247.1 acres (move decimal two places!)
• Common error: Forgetting km² is very large compared to acres
• Example: 10 km² = 2,471 acres, NOT 24.7 acres
• Tool: km² to acres converter

❌ Mistake #5: Confusing Area with Distance

• Wrong: Thinking "1 km²" means "1 km by 1 km by 1 km"
• Correct: 1 km² is 2D area (1 km × 1 km), not 3D volume
• Area: Square kilometers measure surface area (2 dimensions)
• Volume: Cubic kilometers (km³) measure volume (3 dimensions)
• Example: A city's area is km², but a lake's volume is km³

❌ Mistake #6: Using Wrong Unit for Property

• Wrong: Describing a house lot as "0.001 km²"
• Correct: Use hectares (0.1 ha) or m² (1,000 m²) for properties
• Better: Use acres or square feet for smaller areas
• When to use km²: Only for very large areas (cities, countries, regions)
• When NOT to use km²: Individual properties, buildings, small parcels