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Square Kilometer to Acre Conversion Calculator: Free Online Tool

Convert square kilometers to acres with our free online area converter.

Square Kilometer to Acre Calculator

Square Kilometer
Acre

How to Use the Calculator:

  1. Enter the value you want to convert in the 'From' field (Square Kilometer).
  2. The converted value in Acre will appear automatically in the 'To' field.
  3. Use the dropdown menus to select different units within the Area category.
  4. Click the swap button (⇌) to reverse the conversion direction.

How to Convert Square Kilometer to Acre

Converting Square Kilometer to Acre involves multiplying the value by a specific conversion factor, as shown in the formula below.

Formula:

1 Square Kilometer = 247.1054 acres

Example Calculation:

Convert 10 square kilometers: 10 × 247.1054 = 2471.054 acres

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.

What is a Square Kilometer and a Acre?

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)
  • 1 km² ≈ 247.1 acres (ac)

The acre (symbol: ac) is a unit of land area used in the imperial and US customary systems. It is traditionally defined as the area of one chain by one furlong (66 by 660 feet). This is exactly equal to:

  • 10 square chains
  • 1/640 of a square mile
  • 4,840 square yards
  • 43,560 square feet
  • Approximately 4,046.856 square meters (m²)
  • Approximately 0.4047 hectares (ha)

While derived from traditional farming practices, its size is now legally defined based on the international yard.

Note: The Square Kilometer is part of the metric (SI) system, primarily used globally in science and trade. The Acre belongs to the imperial/US customary system.

History of the Square Kilometer and Acre

  • 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.
  • 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. 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.
  • 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.
  • Global Usage: Today, the square kilometer is the predominant unit used worldwide for measuring the land area of countries, large administrative regions, bodies of water, and other significant geographical features.
  • Origin: The word "acre" derives from the Old English word æcer (originally meaning "open field"), cognate with German Acker and Latin ager. It traditionally represented the amount of land that could be ploughed by one man with one yoke of oxen in one day. This practical definition naturally led to considerable variation in its size depending on the land quality and local customs.
  • Medieval Variations: Throughout the Middle Ages in England, the acre's size varied. Different regions used "customary acres" based on local practices, often related to the quality of the land or the length of a standard furrow (furlong).
  • Standardization (Gunter's Chain): The standardization of the acre is closely linked to the invention of Gunter's chain in 1620. This measuring chain, 66 feet long (divided into 100 links), became a standard survey tool. The traditional definition of an acre as a strip of land one furlong (10 chains or 660 feet) long and one chain (66 feet) wide was easily measured using the chain. This area is precisely 10 square chains.
  • Statutory Acre: In England and Wales, the Weights and Measures Act of 1878 formalized the "statutory acre" based on the imperial yard, solidifying the definition as 4,840 square yards (or 43,560 square feet). This is the acre commonly used today in the UK, US, and Commonwealth countries.
  • Metrication: Although many countries using the acre have largely adopted the metric system for other measurements, the acre persists strongly in land transactions and agriculture due to historical precedent and cultural familiarity. The hectare (10,000 m²) is the more common metric unit for land.

Common Uses for square kilometers and acres

Explore the typical applications for both Square Kilometer (metric) and Acre (imperial/US) to understand their common contexts.

Common Uses for square kilometers

The square kilometer is almost exclusively used for measuring large-scale areas:

  • Geography and Cartography: The standard unit for stating the land or surface area of countries, continents, large islands, administrative divisions (states, provinces), and major cities.
  • Demography: Essential for calculating population density, typically expressed as inhabitants per square kilometer (people/km²).
  • Environmental Science: Measuring the extent of large ecosystems (forests, deserts, wetlands), national parks, conservation areas, watersheds, ice sheets, or the area impacted by large-scale environmental events (e.g., oil spills, deforestation).
  • Urban Planning and Land Management: Quantifying large zones, districts, or total city area in regional planning.
  • Geology and Planetary Science: Measuring the surface area of large geological formations or the surface areas of planets, moons, and asteroids.
  • Military and Logistics: Defining large operational areas or zones.

It is too large for measuring individual properties, farms (hectares or acres are preferred), or room sizes (square meters or square feet are used).

Common Uses for acres

The acre remains a primary unit for land measurement in several countries, particularly within specific sectors:

  • Real Estate (US, UK, Commonwealth): Standard unit for describing the size of land parcels in property listings, deeds, and surveys, especially for residential lots larger than typical city plots, rural properties, and undeveloped land.
  • Agriculture: Widely used by farmers to measure field sizes, calculate crop yields, allocate resources (like fertilizer or seeds), and comply with agricultural regulations.
  • Land Management and Planning: Used in zoning regulations, environmental assessments, and land development projects to specify area requirements or limitations.
  • Historical Documents: Understanding the acre is crucial for interpreting historical land records, surveys, and deeds.
  • Informal Comparisons: Often used informally to help visualize the size of large areas, even where metric units are officially standard.

Frequently Asked Questions

Questions 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. This is calculated as 1,000 meters × 1,000 meters.

How many hectares are in one square kilometer?

There are exactly 100 hectares (ha) in one square kilometer. (1 km² = 1,000,000 m² and 1 ha = 10,000 m²).

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
  • Example: 100 km² ≈ 100 × 0.386102 mi² ≈ 38.61 mi²

Conversely, to convert square miles to square kilometers, multiply by approximately 2.58999.

  • 1 mi² ≈ 2.59 km²

Is the square kilometer an official SI unit?

Strictly speaking, the official SI derived unit for area is the square meter (m²). However, the square kilometer (km²) is formed by combining an SI prefix (kilo-) with the SI base unit (meter) raised to the power of two, making it a standard and fully accepted multiple within the metric system and for use alongside SI units.

What is the difference between a kilometer and a square kilometer?

A kilometer (km) is a unit of length or distance (one dimension). A square kilometer (km²) is a unit of area (two dimensions), representing a square with sides of one kilometer each.

About Acre (acre)

How big is an acre visually?

An acre is 43,560 square feet. While it can be any shape, a square acre would be about 208.71 feet on each side. A common visual comparison is an American football field: one acre is about 90.75% of the total area of a standard American football field (which is 120 yards long by 53.33 yards wide, or 57,600 sq ft including end zones). Excluding the end zones (100 yards by 53.33 yards, or 48,000 sq ft), an acre is about 90.75% of the playing field area.

How many square feet are in an acre?

There are exactly 43,560 square feet in one acre. This definition (1 furlong × 1 chain = 660 ft × 66 ft) is precise.

How many square yards are in an acre?

There are exactly 4,840 square yards in one acre (since 1 yard = 3 feet, 1 square yard = 9 square feet; 43,560 / 9 = 4,840).

How many acres are in a square mile?

There are exactly 640 acres in one square mile.

How many acres are in a hectare?

One hectare is equal to 10,000 square meters. Since one acre is approximately 4,046.856 square meters, one hectare contains approximately 2.471 acres (10,000 / 4046.856 ≈ 2.471). Conversely, one acre is approximately 0.4047 hectares.

Is the acre an SI unit?

No, the acre is not part of the International System of Units (SI). It belongs to the imperial and US customary systems. The SI unit for area is the square meter (m²). For land measurement, the hectare (ha), equal to 10,000 m², is commonly used in metric contexts and is accepted for use with SI.

Conversion Table: Square Kilometer to Acre

Square Kilometer (km²)Acre (acre)
1247.105
51,235.527
102,471.054
256,177.635
5012,355.269
10024,710.538
500123,552.691
1,000247,105.382

All Area Conversions

Square Meter to Square KilometerSquare Meter to Square CentimeterSquare Meter to Square MillimeterSquare Meter to Square InchSquare Meter to Square FootSquare Meter to Square YardSquare Meter to Square MileSquare Meter to AcreSquare Meter to HectareSquare Kilometer to Square MeterSquare Kilometer to Square CentimeterSquare Kilometer to Square MillimeterSquare Kilometer to Square InchSquare Kilometer to Square FootSquare Kilometer to Square YardSquare Kilometer to Square MileSquare Kilometer to HectareSquare Centimeter to Square MeterSquare Centimeter to Square KilometerSquare Centimeter to Square MillimeterSquare Centimeter to Square InchSquare Centimeter to Square FootSquare Centimeter to Square YardSquare Centimeter to Square MileSquare Centimeter to AcreSquare Centimeter to HectareSquare Millimeter to Square MeterSquare Millimeter to Square KilometerSquare Millimeter to Square CentimeterSquare Millimeter to Square InchSquare Millimeter to Square FootSquare Millimeter to Square YardSquare Millimeter to Square MileSquare Millimeter to AcreSquare Millimeter to HectareSquare Inch to Square MeterSquare Inch to Square KilometerSquare Inch to Square CentimeterSquare Inch to Square MillimeterSquare Inch to Square FootSquare Inch to Square YardSquare Inch to Square MileSquare Inch to AcreSquare Inch to HectareSquare Foot to Square MeterSquare Foot to Square KilometerSquare Foot to Square CentimeterSquare Foot to Square MillimeterSquare Foot to Square InchSquare Foot to Square YardSquare Foot to Square MileSquare Foot to AcreSquare Foot to HectareSquare Yard to Square MeterSquare Yard to Square KilometerSquare Yard to Square CentimeterSquare Yard to Square MillimeterSquare Yard to Square InchSquare Yard to Square FootSquare Yard to Square MileSquare Yard to AcreSquare Yard to HectareSquare Mile to Square MeterSquare Mile to Square KilometerSquare Mile to Square CentimeterSquare Mile to Square MillimeterSquare Mile to Square InchSquare Mile to Square FootSquare Mile to Square YardSquare Mile to AcreSquare Mile to HectareAcre to Square MeterAcre to Square KilometerAcre to Square CentimeterAcre to Square MillimeterAcre to Square InchAcre to Square FootAcre to Square YardAcre to Square MileAcre to HectareHectare to Square MeterHectare to Square KilometerHectare to Square CentimeterHectare to Square MillimeterHectare to Square InchHectare to Square FootHectare to Square YardHectare to Square MileHectare to Acre

Other Units from Area