What is are?
An are is a metric unit of area equal to 100 square metres. While largely replaced by the hectare for most practical uses, it is still referenced in some European countries for measuring agricultural plots.
Real-world uses
The are (100 m²) is used in some European countries for small land parcels and garden plots. In France, small agricultural plots and building lots may be listed in ares. It is most commonly encountered as the basis for the hectare (100 ares).
History
The are was defined in 1795 during the creation of the metric system in France as 100 square metres. Though the hectare eclipsed it in common usage, the are remains a legally recognized metric unit in several European countries.
Common mistakes
Confusing the are (a unit of area equal to 100 m²) with the word "are" (verb). Also, many people are unfamiliar with this unit and do not realize that 1 hectare = 100 ares.
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.
When is this conversion used?
Converting are to square kilometre is useful in the area domain when comparing values across different measurement standards or applying formulas that require a specific unit.
Worked examples
1 are = 0.0001 square kilometre
1 square kilometre = 1,000,000 square metre
How to convert are to square kilometre
To convert are to square kilometre, multiply the value by 0.0001.
To convert square kilometre back to are, multiply by 10,000.
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: are to square kilometre
| are | square kilometre |
|---|---|
| 0.1 | 0.00001 |
| 0.5 | 0.00005 |
| 1 | 0.0001 |
| 2 | 0.0002 |
| 5 | 0.0005 |
| 10 | 0.001 |
| 25 | 0.0025 |
| 50 | 0.005 |
| 100 | 0.01 |
| 250 | 0.025 |
| 500 | 0.05 |
| 1,000 | 0.1 |
Common values
| are | square kilometre | |
|---|---|---|
| A4 paper | 0.00062 are | 6.200000e-08 square kilometre |
| Parking space | 0.125 are | 0.0000125 square kilometre |
| Tennis court | 2.6087 are | 0.00026087 square kilometre |
| Football field (soccer) | 71.4 are | 0.00714 square kilometre |
| Central Park, NYC | 34,100 are | 3.41 square kilometre |