What is square kilometre?

A square kilometre is a metric unit of area equal to one million square metres. It is used for measuring large geographic areas such as countries, forests, lakes, and urban zones.

Real-world uses

Square kilometres are used for country areas, city boundaries, national park sizes, and deforestation tracking. Geographic and environmental data, including satellite imagery resolution, reference areas in km². Singapore is about 733 km², for scale.

History

The square kilometre became the standard large-area unit with global metrication, replacing traditional units like the square league. It is the preferred unit for geographic and political area comparisons in international statistics and the United Nations system.

Common mistakes

Thinking 1 km² = 1,000 m². It is actually 1,000,000 m² (1 km × 1 km). Also, confusing square kilometres with kilometres squared in conversation, though mathematically they mean the same thing.

What is acre?

An acre is a unit of area in imperial and US customary systems equal to 43,560 square feet. It is the standard unit for measuring agricultural land, property lots, and parks in the United States and United Kingdom.

Real-world uses

Acres are used for land parcels, farm sizes, and real estate in the US, UK, and some Commonwealth countries. Zoning laws often specify minimum lot sizes in acres. An American football field (including end zones) is about 1.32 acres.

History

The acre originated in medieval England as the amount of land a yoke of oxen could plough in one day. The word comes from Old English "æcer." It was standardized as a strip 1 furlong (660 ft) by 1 chain (66 ft), yielding 43,560 square feet.

Common mistakes

Assuming an acre is a square measure with specific dimensions—it is 43,560 sq ft but can be any shape. Also, confusing acres with hectares: 1 acre ≈ 0.405 hectares, so roughly 2.5 acres make one hectare.

When is this conversion used?

Converting between square kilometre and acre is common when working across metric and imperial systems, such as international trade, travel between countries with different measurement standards, or following instructions from a different region.

Worked examples

1 square kilometre = 247.10538147 acre

1 acre = 4,046.8564224 square metre

How to convert square kilometre to acre

To convert square kilometre to acre, multiply the value by 247.10538147.

To convert acre back to square kilometre, multiply by 0.00404686.

Measurement standards

The square metre is the SI derived unit of area. The hectare (10,000 m²) is accepted for use with the SI by the BIPM, particularly for land measurement, though it is not an SI unit itself.

Did you know?

Vatican City, the world's smallest independent state, covers just 0.44 km² (about 109 acres) — smaller than many golf courses. By contrast, Russia spans over 17.1 million km², nearly 39 million times larger.

Quick reference: square kilometre to acre

Common values

Available Area units

• square metre conversions
• square kilometre conversions
• square foot conversions
• square mile conversions
• acre conversions
• hectare conversions
• square centimetre conversions
• square inch conversions
• square yard conversions
• are conversions

More square kilometre conversions

• Convert square kilometre to square metre
• Convert square kilometre to square foot
• Convert square kilometre to square mile
• Convert square kilometre to acre
• Convert square kilometre to hectare
• Convert square kilometre to square centimetre
• Convert square kilometre to square inch
• Convert square kilometre to square yard
• Convert square kilometre to are