Conversion from Square meters to Hectares

Information about the Square meter (m²)

The square metre is the SI unit of area, written m². It is the area of a square whose sides each measure one metre, and because the metre is a base unit, every other area unit in the system is derived from it by squaring a length. It is the unit in which most of the world buys homes, specifies materials and describes land.

Property is its largest everyday use. Outside the United States and, in part, the United Kingdom, dwellings are advertised, taxed and compared by their floor area in square metres, and price per square metre is the standard way of comparing one district with another. A modest one-bedroom flat runs to about 45 square metres, a family house between 100 and 150, and a single parking space takes up roughly 12.5.

Materials are sold and specified by the square metre because coverage, not volume, is what a builder needs to know. A litre of emulsion paint covers about ten square metres, floor tiles and laminate are priced by the square metre, and insulation is rated by its thermal resistance per square metre. Paper carries its own version of the same idea: the weight of a sheet stock is given in grams per square metre, so 80 g/m² office paper and 300 g/m² card are compared on one scale.

Physics uses the square metre as the denominator of almost every flux. Solar irradiance at the earth's surface peaks near 1000 watts per square metre, which is the figure solar panels are rated against. Pressure is force per square metre, and one newton per square metre is one pascal by definition. Heat loss through a wall is quoted in watts per square metre per kelvin, and sound intensity in watts per square metre.

Medicine uses it for the human body. An adult's skin covers between 1.6 and 2.0 square metres, and that figure is calculated for each patient before chemotherapy, because many drug doses are prescribed in milligrams per square metre rather than per kilogram. Burn severity is assessed as the percentage of body surface affected, using the same underlying measurement.

Where imperial units survive, the square foot competes directly with it. American and British commercial property is still let by the square foot, and one square metre is 10.76 square feet, which is why converted figures rarely come out round. Land at a larger scale moves to the hectare, equal to 10,000 square metres, and then to the square kilometre.

One square metre equals 10,000 square centimetres, about 10.764 square feet, about 1.196 square yards, or 0.0001 hectares.

Information about the Hectare (ha)

The hectare is a unit of area equal to 10,000 square metres, written ha. It is a square one hundred metres on a side. It is not strictly an SI unit, but the International Bureau of Weights and Measures accepts it for use with the SI in the one field where it is indispensable: the measurement of land.

It descends from the are, a unit of one hundred square metres introduced in revolutionary France in 1795. The are proved too small for fields and the square kilometre too large, so the hundredfold multiple settled into the gap and outlived its parent entirely. Today almost nobody writes ares, while hectares appear on title deeds, farm subsidies and environmental reports across most of the world.

Agriculture is built on it. Crop yields are quoted in tonnes per hectare, and the figures carry a great deal of information in very little space: wheat in north-western Europe runs to about eight tonnes per hectare, against a world average nearer three. Wine appellations cap production in hectolitres per hectare, and European farm support has been paid per hectare rather than per tonne since the 1990s, which changed what farmers grew as much as any agronomic advance.

Environmental accounting uses the same unit. Deforestation, wetland loss, protected area and reforestation targets are all reported in hectares, because the quantity is large enough to describe a forest and small enough to describe a field. Urban planning uses it inverted, as dwellings per hectare, which is the standard way of comparing the density of one development with another.

For a sense of scale, an association football pitch of the usual size covers about 0.7 hectares, so a hectare is roughly a pitch and a half. A hectare of productive farmland feeds a handful of people on a mixed diet, and a hectare of dense city holds several hundred residents. Traditional Japanese and Korean land measures happen to land close by: one chō and one jeongbo are both about 0.99 hectares.

The imperial competitor is the acre, and the two do not convert cleanly: one hectare is 2.471 acres, and one acre is 0.4047 hectares. Where both systems are in use, as in Ireland, parts of Canada and much of South Asia, land is often quoted in both, and the conversion factor is one of the few worth committing to memory.

One hectare equals 10,000 square metres, about 2.471 acres, 0.01 square kilometres, or about 107,639 square feet.