Acre to Square Kilometer Converter
Convert acres to square kilometers with our free online area converter.
Quick Answer
1 Acre = 0.004047 square kilometers
Formula: Acre × conversion factor = Square Kilometer
Use the calculator below for instant, accurate conversions.
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Acre to Square Kilometer Calculator
How to Use the Acre to Square Kilometer Calculator:
- Enter the value you want to convert in the 'From' field (Acre).
- The converted value in Square Kilometer will appear automatically in the 'To' field.
- Use the dropdown menus to select different units within the Area category.
- Click the swap button (⇌) to reverse the conversion direction.
How to Convert Acre to Square Kilometer: Step-by-Step Guide
Converting Acre to Square Kilometer involves multiplying the value by a specific conversion factor, as shown in the formula below.
Formula:
1 Acre = 0.00404686 square kilometersExample Calculation:
Convert 10 acres: 10 × 0.00404686 = 0.0404686 square kilometers
Disclaimer: For Reference Only
These conversion results are provided for informational purposes only. While we strive for accuracy, we make no guarantees regarding the precision of these results, especially for conversions involving extremely large or small numbers which may be subject to the inherent limitations of standard computer floating-point arithmetic.
Not for professional use. Results should be verified before use in any critical application. View our Terms of Service for more information.
Need to convert to other area units?
View all Area conversions →What is a Acre and a Square Kilometer?
The Mathematical Definition
1 Acre = 43,560 square feet
This definition comes from the traditional measurement:
- 1 chain = 66 feet (Gunter's chain)
- 1 furlong = 660 feet (10 chains)
- 1 acre = 1 chain × 1 furlong = 66 ft × 660 ft = 43,560 sq ft
In Other Units:
- Square Yards: $\frac{43,560}{9} = 4,840 \text{ sq yd}$
- Square Meters: $43,560 \times 0.09290304 = 4,046.856 \text{ m}^2$
- Hectares: $\frac{4,046.856}{10,000} = 0.4047 \text{ ha}$
Shape Doesn't Matter
An acre can be any shape as long as the total area is 43,560 sq ft.
- Square Acre: 208.71 ft × 208.71 ft
- Rectangular Acre: 66 ft × 660 ft (traditional furlong × chain)
- Circular Acre: Radius of 117.75 ft
- Irregular Acre: Any polygon with 43,560 sq ft area
The "Chain" System
The acre is part of an elegant measurement system based on Gunter's chain:
- 1 link = 7.92 inches (0.66 ft)
- 1 chain = 100 links = 66 ft
- 1 furlong = 10 chains = 660 ft = 1/8 mile
- 1 mile = 8 furlongs = 80 chains = 5,280 ft
- 1 acre = 10 square chains
This system made surveying incredibly efficient. A surveyor could measure land using a physical chain and easily calculate acreage.
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
Note: The Acre is part of the imperial/US customary system, primarily used in the US, UK, and Canada for everyday measurements. The Square Kilometer belongs to the metric (SI) system.
History of the Acre and Square Kilometer
: From Oxen to GPS
Ancient Origins
The concept of measuring land by how much could be worked in a day is ancient and universal:
- Roman Jugerum: The area two oxen could plow in one day (~2/3 acre).
- German Morgen: "Morning's work" of plowing (~0.6-0.9 acres).
- French Arpent: Regional French unit (~0.85 acres).
- English Acre: The amount one man with one ox could plow in one day.
The problem? Soil quality varied. Rocky, hilly land took longer to plow than flat, fertile land. This led to regional variations in the "acre."
Medieval Chaos
In medieval England, there were dozens of different "acres":
- Statute Acre: 43,560 sq ft (the modern standard).
- Irish Acre: 7,840 sq yd (1.62 statute acres).
- Scottish Acre: 6,150 sq yd (1.27 statute acres).
- Cheshire Acre: 10,240 sq yd (2.11 statute acres).
- Cornish Acre: Varied by location.
Land disputes were common because nobody could agree on the size of an acre!
The Gunter Revolution (1620)
Edmund Gunter, an English clergyman and mathematician, invented the surveyor's chain in 1620. This 66-foot chain (divided into 100 links) became the standard tool for land measurement.
Why 66 feet?
- 1 chain = 4 rods (or poles) = 66 feet.
- 10 chains = 1 furlong = 660 feet = 1/8 mile.
- 80 chains = 1 mile = 5,280 feet.
This made calculations trivial:
- 1 acre = 10 square chains.
- 640 acres = 1 square mile.
The Homestead Act (1862)
In the United States, the Homestead Act of 1862 granted 160 acres of public land to settlers who would farm it for 5 years. This "quarter section" (1/4 of a square mile) became the iconic American farm size.
The Grid System:
- 1 section = 1 square mile = 640 acres.
- 1 quarter section = 160 acres (homestead).
- 1 township = 36 sections = 23,040 acres = 36 square miles.
This grid system is why much of the American Midwest has perfectly straight roads running north-south and east-west.
Modern Standardization
- 1878: Weights and Measures Act (UK) formalized the "statutory acre."
- 1959: International yard and pound agreement standardized the acre globally.
- Today: The acre is legally defined as exactly 4,046.8564224 square meters.
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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).
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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.
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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.
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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).
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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.
Common Uses and Applications: acres vs square kilometers
Explore the typical applications for both Acre (imperial/US) and Square Kilometer (metric) to understand their common contexts.
Common Uses for acres
1. Real Estate
The acre is the standard unit for land sales in the US, UK, Canada, and Australia.
Residential:
- Lot sizes for homes, especially in suburban and rural areas.
- Zoning regulations often specify minimum lot sizes in acres (e.g., "R-1 zoning: 1-acre minimum").
Commercial:
- Shopping centers, office parks, industrial sites.
- "10-acre commercial development site available."
Undeveloped Land:
- Timberland, hunting land, investment property.
- "40-acre wooded parcel with creek frontage."
2. Agriculture
Farmers use acres to:
- Measure field sizes: "I have 80 acres in corn this year."
- Calculate yields: "We harvested 180 bushels per acre."
- Apply inputs: "Apply 150 lbs of nitrogen per acre."
- Comply with regulations: "You must leave 10 acres fallow for conservation."
Crop Yields (US Average):
- Corn: 177 bushels/acre.
- Soybeans: 52 bushels/acre.
- Wheat: 47 bushels/acre.
- Cotton: 900 lbs/acre.
3. Forestry
Timber is sold by the acre.
- Managed Forest: "200 acres of pine plantation."
- Timber Yield: "This stand will produce 20 cords per acre."
4. Land Management & Conservation
- National Parks: Measured in acres (Yellowstone: 2.2 million acres).
- Wetlands: "Restore 500 acres of wetlands."
- Wildlife Habitat: "Preserve 1,000 acres for endangered species."
5. Sports & Recreation
- Golf Courses: 100-200 acres (18 holes).
- Ski Resorts: "1,500 acres of skiable terrain."
- Hunting Leases: "Lease 500 acres for deer hunting."
When to Use square kilometers
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
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
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.
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
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
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
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
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
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
Additional Unit Information
About Acre (acre)
How big is an acre visually?
The easiest way to visualize an acre:
- Football Field: An acre is about 90.75% of an American football field (including end zones). The field is 120 yards × 53.33 yards = 57,600 sq ft. An acre is 43,560 sq ft.
- Square: A square acre is 208.71 feet on each side. That's about 70 yards × 70 yards.
- Walking: You can walk the perimeter of a square acre in about 3-4 minutes at a normal pace.
How many houses fit on an acre?
Depends on lot size and zoning:
- Urban (Small Lots): 8-12 houses (4,000-5,000 sq ft lots).
- Suburban (Standard): 4-6 houses (7,000-10,000 sq ft lots).
- Suburban (Large): 2-3 houses (15,000-20,000 sq ft lots).
- Rural (Estate): 1 house (entire acre or more).
Zoning Example:
- R-1 (Low Density): 1-2 units per acre.
- R-2 (Medium Density): 4-8 units per acre.
- R-3 (High Density): 12-20 units per acre.
How many acres is a football field?
American Football Field:
- With end zones: 120 yards × 53.33 yards = 57,600 sq ft = 1.32 acres.
- Without end zones: 100 yards × 53.33 yards = 48,000 sq ft = 1.10 acres.
Soccer Field (FIFA):
- Regulation: 100-130 yards × 50-100 yards.
- Typical: 110 yards × 70 yards = 56,700 sq ft = 1.30 acres.
How many acres is a city block?
Varies wildly by city:
- Manhattan (NYC): 2-5 acres (blocks are irregular).
- Chicago: ~3 acres (660 ft × 330 ft blocks).
- Portland: ~2 acres (200 ft × 200 ft blocks).
- Phoenix: ~4 acres (larger grid).
Rule of Thumb: Most US city blocks are 2-5 acres.
How many acres do I need for a house?
Minimum (Legal):
- Urban: 0.1 acres (4,356 sq ft) - typical city lot.
- Suburban: 0.25-0.5 acres - standard suburban lot.
- Rural: 1+ acres - zoning often requires minimum acreage.
Practical:
- Comfortable Home: 0.5-1 acre (room for yard, garden, privacy).
- Hobby Farm: 5-10 acres (horses, chickens, large garden).
- Self-Sufficiency: 10-20 acres (livestock, crops, timber).
How many acres do you need for farming?
Depends on the type of farming:
- Market Garden (Vegetables): 1-5 acres (intensive).
- Orchard: 5-20 acres.
- Cattle (Pasture): 1.5-2 acres per cow (varies by climate/grass quality).
- Grain Farming: 100-1,000+ acres (mechanized).
- Dairy Farm: 50-500 acres (depends on herd size).
USDA Definition of a Farm: Any place that produced and sold at least $1,000 of agricultural products during the year. This can be as small as 1 acre of intensive vegetables or as large as 10,000 acres of wheat.
How do you calculate acreage from dimensions?
For Rectangular Land: $$ \text{Acres} = \frac{\text{Length (ft)} \times \text{Width (ft)}}{43,560} $$
Example: A lot is 200 ft × 300 ft. $$ \frac{200 \times 300}{43,560} = \frac{60,000}{43,560} = 1.38 \text{ acres} $$
For Irregular Shapes:
- Divide the land into triangles or rectangles.
- Calculate the area of each section.
- Add them together.
- Divide by 43,560.
Modern Method: Use GPS or GIS software to trace the boundary and calculate area automatically.
Is an acre the same in all countries?
Mostly yes, but with variations:
- US/UK Acre (Statute Acre): 43,560 sq ft (standard).
- Irish Acre: 7,840 sq yd = 70,560 sq ft = 1.62 statute acres (historical, rarely used today).
- Scottish Acre: 6,150 sq yd = 55,350 sq ft = 1.27 statute acres (historical).
- Acre (International): Since 1959, the "international acre" is standardized at 4,046.8564224 m².
Today: When someone says "acre" without qualification, they mean the statute acre (43,560 sq ft).
Why is an acre 43,560 square feet?
It comes from the furlong × chain definition:
- 1 furlong = 660 feet (1/8 mile, the length of a traditional plowed furrow).
- 1 chain = 66 feet (Gunter's surveying chain).
- 1 acre = 1 furlong × 1 chain = 660 ft × 66 ft = 43,560 sq ft.
This was chosen because it made surveying easy with Gunter's chain (which was exactly 1 chain long).
How many acres is Central Park?
Central Park (New York City): 843 acres (1.317 square miles).
- Length: 2.5 miles (north-south).
- Width: 0.5 miles (east-west).
- Perimeter: ~6 miles.
For comparison:
- Golden Gate Park (San Francisco): 1,017 acres (20% larger than Central Park).
- Hyde Park (London): 350 acres.
About Square Kilometer (km²)
How many square meters are in one square kilometer?
There are exactly 1,000,000 square meters (m²) in one square kilometer.
Calculation: 1 km² = 1,000 m × 1,000 m = 1,000,000 m²
Conversion:
- 1 km² = 1,000,000 m²
- 0.1 km² = 100,000 m²
- 0.01 km² = 10,000 m²
- Example: 2.5 km² = 2,500,000 m²
Use our square kilometer to square meter converter for instant conversions.
How many hectares are in one square kilometer?
There are exactly 100 hectares (ha) in one square kilometer.
Why: 1 km² = 1,000,000 m² and 1 ha = 10,000 m², therefore: 1 km² = 1,000,000 m² ÷ 10,000 m²/ha = 100 ha
Conversion examples:
- 1 km² = 100 hectares
- 10 km² = 1,000 hectares
- 0.5 km² = 50 hectares
- 2.5 km² = 250 hectares
When to use which:
- Hectares: Farms, parks, smaller land areas (1-1,000 ha)
- Square kilometers: Cities, regions, countries (0.1+ km²)
Convert between them: km² to hectares | Hectares to km²
How do you convert square kilometers to square miles?
To convert square kilometers to square miles, multiply the area in square kilometers by approximately 0.386102.
Conversion formula: Area [mi²] ≈ Area [km²] × 0.386102
Examples:
- 1 km² ≈ 0.386 mi²
- 10 km² ≈ 3.86 mi²
- 100 km² ≈ 38.6 mi²
- 1,000 km² ≈ 386 mi²
Reverse conversion (square miles to square kilometers):
- Multiply by approximately 2.58999
- 1 mi² ≈ 2.59 km²
Why this factor?:
- 1 km = 0.621371 miles
- 1 km² = (0.621371)² = 0.386102 mi²
Use our km² to mi² converter for accurate conversions without manual calculation.
Is the square kilometer an official SI unit?
Technically, the official SI derived unit for area is the square meter (m²).
However, the square kilometer (km²) is a standard and fully accepted multiple within the metric system and for use alongside SI units.
Why it's accepted:
- Formed by combining an SI prefix (kilo-) with the SI base unit (meter) raised to the power of two
- Follows SI conventions and decimal scaling
- Listed in SI documentation as a "unit accepted for use with SI"
- Used universally in scientific, technical, and official applications
In practice:
- m² is the "base" SI unit for area
- km² is the practical unit for large areas
- Both are fully part of the international metric system
What is the difference between a kilometer and a square kilometer?
Kilometer (km) is a unit of length or distance (one dimension). Square kilometer (km²) is a unit of area (two dimensions).
The difference:
Kilometer (km) - 1D:
- Measures distance, length, height
- Examples: Road length, height of mountain, distance between cities
- Linear measurement
Square Kilometer (km²) - 2D:
- Measures area, surface
- Examples: Size of a country, area of a lake, extent of a forest
- Represents a square with sides of one kilometer each
Key distinction:
- 10 km might be the distance from point A to point B
- 10 km² might be the area of a small town
Analogy:
- Kilometer is like measuring the perimeter of a fence
- Square kilometer is like measuring the area inside the fence
How big is 1 square kilometer visually?
1 square kilometer (km²) is a square with sides exactly 1 kilometer (1,000 meters) long.
Visual comparisons:
- 100 American football fields (including end zones)
- About 150 soccer/football fields
- 0.39 square miles (just over 1/3 of a square mile)
- 247 acres (almost 250 acres)
- A 10-minute walk around the perimeter (4 km)
In city terms:
- Small to medium neighborhood
- 2-4 city blocks (in large US cities)
- Area you could see from a tall building
- Walking distance of 15-20 minutes to cross
In rural terms:
- Large farm
- Small village area
- Several hundred house lots
Perspective:
- Central Park (NYC): 3.41 km²
- Vatican City: 0.44 km²
- Monaco: 2.02 km²
How to visualize: Imagine walking 1 km north, then 1 km east, then 1 km south, then 1 km west back to start - the area inside is 1 km².
What is 100 km² equivalent to?
100 square kilometers = 38.6 square miles = 10,000 hectares = 24,710 acres
City examples (approximately 100 km² or close):
- Paris (city proper): 105 km²
- Washington, D.C.: 177 km²
- Boston: 232 km²
- San Francisco: 121 km²
- Miami: 143 km²
- Manhattan: 59 km² (about 60% of 100 km²)
Country examples (small island nations):
- Maldives: 300 km² (about 3 times)
- Grenada: 344 km² (about 3.5 times)
- Saint Vincent: 389 km² (about 4 times)
Natural features:
- Medium-sized lake
- Large national park or nature reserve
- Small island
- Significant forest area
Population examples:
- At urban density (5,000 people/km²): 500,000 people
- At suburban density (1,000 people/km²): 100,000 people
- At rural density (50 people/km²): 5,000 people
Practical understanding:
- Medium-sized city or large town
- Area you could drive across in 15-30 minutes
- Typical county in smaller US states
Convert 100 km²: to square miles | to hectares
How do you calculate the area in square kilometers?
Basic formula for rectangles: Area (km²) = Length (km) × Width (km)
Step-by-step process:
1. Measure dimensions:
- Measure length and width in kilometers
- If measured in meters, divide by 1,000 to get kilometers
- If measured in miles, multiply by 1.609 to get kilometers
2. Calculate:
- Multiply length by width
- Result is in square kilometers
Examples:
Example 1 - Simple rectangle:
- Length: 5 km
- Width: 3 km
- Area = 5 km × 3 km = 15 km²
Example 2 - From meters:
- Length: 2,500 meters = 2.5 km
- Width: 4,000 meters = 4 km
- Area = 2.5 km × 4 km = 10 km²
Example 3 - From miles:
- Length: 6 miles = 9.66 km
- Width: 4 miles = 6.44 km
- Area = 9.66 km × 6.44 km ≈ 62.2 km²
For complex shapes:
Circle:
- Area = π × radius²
- If radius = 5 km: Area = 3.14159 × 5² ≈ 78.5 km²
Irregular shapes:
- Divide into triangles/rectangles
- Calculate each section
- Add all sections together
- Or use GIS/mapping software
Using GPS coordinates:
- Use online area calculators
- Import coordinates into GIS software
- Software calculates irregular polygons automatically
Verification:
- Use our area converter to check your calculations
- Convert to other units to verify makes sense
What countries are about 1,000 km²?
Countries close to 1,000 km² (between 500-1,500 km²):
Very close to 1,000 km²:
- Hong Kong: 1,104 km²
- Samoa: 2,842 km²
- Luxembourg: 2,586 km²
- Mauritius: 2,040 km²
Between 500-1,000 km²:
- Singapore: 728 km²
- Bahrain: 778 km²
- Kiribati: 811 km²
- Tonga: 747 km²
- Federated States of Micronesia: 702 km²
- Saint Lucia: 617 km²
- Andorra: 468 km²
Between 1,000-1,500 km²:
- Cape Verde: 4,033 km²
- Trinidad and Tobago: 5,131 km²
- Comoros: 1,862 km²
- São Tomé and Príncipe: 964 km²
For comparison:
- 1,000 km² = 386 square miles
- About the size of Hong Kong or 10x the size of Paris
- Smaller than most US counties
- Medium-sized metropolitan area
Interesting fact: Only about 30 countries are smaller than 1,000 km², mostly island nations and microstates.
How many acres is a square kilometer?
1 square kilometer = 247.105 acres (commonly rounded to 247 acres)
Conversion formula: Acres = km² × 247.105
Examples:
- 1 km² = 247 acres
- 5 km² = 1,235 acres
- 10 km² = 2,471 acres
- 100 km² = 24,710 acres
- 0.1 km² = 24.7 acres
Reverse conversion (acres to km²):
- 1 acre = 0.00405 km²
- 100 acres = 0.405 km²
- 1,000 acres = 4.05 km²
- 10,000 acres = 40.5 km²
Perspective:
- A square kilometer is about 247 football fields
- A large farm might be 200-400 acres (0.8-1.6 km²)
- A golf course is typically 50-80 acres (0.2-0.3 km²)
When to use which:
- Acres: US land parcels, farms, developments (< 1,000 acres)
- Square kilometers: Large regions, cities, countries (> 0.5 km²)
Use our converter: km² to acres | Acres to km²
How is square kilometers different from cubic kilometers?
Square Kilometers (km²) and Cubic Kilometers (km³) measure different things:
Square Kilometers (km²) - AREA (2D):
- Measures surface area
- Two-dimensional
- Example: Land area of a country, surface of a lake
- Unit: km × km = km²
Cubic Kilometers (km³) - VOLUME (3D):
- Measures volume or capacity
- Three-dimensional
- Example: Volume of water in a lake, ice in a glacier
- Unit: km × km × km = km³
Real-world examples:
Lake Michigan:
- Area (surface): 58,000 km²
- Volume (water): 4,920 km³
Amazon Rainforest:
- Area (coverage): 5,500,000 km²
- Volume (if measuring biomass in 3D): Would be km³
City:
- Area (footprint): Measured in km²
- Volume (including buildings/air): Could be km³ (rarely used)
Key differences:
| Feature | km² (Area) | km³ (Volume) | |---------|-----------|--------------| | Dimensions | 2D (length × width) | 3D (length × width × height) | | Measures | Surface area | Space/capacity | | Examples | Country size, lake surface | Water volume, ice volume | | Conversion | 1 km² = 1,000,000 m² | 1 km³ = 1,000,000,000 m³ |
Remember:
- km² = Flat surface measurement
- km³ = 3D space measurement
What is the area of the Earth in square kilometers?
Total Earth surface area: Approximately 510,000,000 km² (510 million km²)
Breakdown:
Water (Oceans and seas):
- Area: ~361,000,000 km² (361 million km²)
- Percentage: ~71% of Earth's surface
- All oceans, seas, lakes combined
Land:
- Area: ~149,000,000 km² (149 million km²)
- Percentage: ~29% of Earth's surface
- All continents and islands
Continents by area:
- Asia: 44,579,000 km²
- Africa: 30,370,000 km²
- North America: 24,709,000 km²
- South America: 17,840,000 km²
- Antarctica: 14,000,000 km² (varies with ice)
- Europe: 10,180,000 km²
- Australia/Oceania: 8,600,000 km²
Oceans by area:
- Pacific: 165,200,000 km²
- Atlantic: 106,460,000 km²
- Indian: 70,560,000 km²
- Southern: 20,327,000 km²
- Arctic: 14,060,000 km²
In other units:
- 510 million km² = 196.9 million mi²
- 510 million km² = 51 billion hectares
Interesting comparisons:
- Russia (largest country): 17 million km² = 3.3% of Earth's surface
- Pacific Ocean alone: 32% of Earth's surface
- All land combined: About the size of the Pacific Ocean + Atlantic Ocean
Note: These are approximate values; exact measurements vary slightly based on sea level, ice coverage, and measurement methodology.
Conversion Table: Acre to Square Kilometer
| Acre (acre) | Square Kilometer (km²) |
|---|---|
| 0.5 | 0.002 |
| 1 | 0.004 |
| 1.5 | 0.006 |
| 2 | 0.008 |
| 5 | 0.02 |
| 10 | 0.041 |
| 25 | 0.101 |
| 50 | 0.202 |
| 100 | 0.405 |
| 250 | 1.012 |
| 500 | 2.023 |
| 1,000 | 4.047 |
People Also Ask
How do I convert Acre to Square Kilometer?
To convert Acre to Square Kilometer, enter the value in Acre in the calculator above. The conversion will happen automatically. Use our free online converter for instant and accurate results. You can also visit our area converter page to convert between other units in this category.
Learn more →What is the conversion factor from Acre to Square Kilometer?
The conversion factor depends on the specific relationship between Acre and Square Kilometer. You can find the exact conversion formula and factor on this page. Our calculator handles all calculations automatically. See the conversion table above for common values.
Can I convert Square Kilometer back to Acre?
Yes! You can easily convert Square Kilometer back to Acre by using the swap button (⇌) in the calculator above, or by visiting our Square Kilometer to Acre converter page. You can also explore other area conversions on our category page.
Learn more →What are common uses for Acre and Square Kilometer?
Acre and Square Kilometer are both standard units used in area measurements. They are commonly used in various applications including engineering, construction, cooking, and scientific research. Browse our area converter for more conversion options.
For more area conversion questions, visit our FAQ page or explore our conversion guides.
Helpful Conversion Guides
Learn more about unit conversion with our comprehensive guides:
All Area Conversions
Other Area Units and Conversions
Explore other area units and their conversion options:
- Square Meter (m²) • Acre to Square Meter
- Square Centimeter (cm²) • Acre to Square Centimeter
- Square Millimeter (mm²) • Acre to Square Millimeter
- Square Inch (in²) • Acre to Square Inch
- Square Foot (ft²) • Acre to Square Foot
- Square Yard (yd²) • Acre to Square Yard
- Square Mile (mi²) • Acre to Square Mile
- Hectare (ha) • Acre to Hectare
Verified Against Authority Standards
All conversion formulas have been verified against international standards and authoritative sources to ensure maximum accuracy and reliability.
National Institute of Standards and Technology — Standards for area measurements
Last verified: December 3, 2025