| Square hectometers (hm²) | Square meters (m²) |
|---|---|
| 1 Square hectometer | 10000 m² |
| 2 Square hectometers | 20000 m² |
| 3 Square hectometers | 30000 m² |
| 4 Square hectometers | 40000 m² |
| 5 Square hectometers | 50000 m² |
| 10 Square hectometers | 100000 m² |
| 20 Square hectometers | 200000 m² |
| 25 Square hectometers | 250000 m² |
| 50 Square hectometers | 500000 m² |
| 100 Square hectometers | 1000000 m² |
| Reference | Square hectometers (hm²) | Square meters (m²) |
|---|---|---|
| A sheet of A4 paper | 0.000006237 hm² | 0.06237 m² |
| A tennis court | 0.02608 hm² | 260.8 m² |
| A football pitch | 0.714 hm² | 7140 m² |
| One hectare | 1 hm² | 10000 m² |
| Central Park, New York | 341 hm² | 3410000 m² |
The square hectometre is a unit of area equal to ten thousand square metres. It is written hm², and it is the area of a square one hundred metres on a side, since a hectometre is one hundred metres. It is exactly one hectare, and the two names describe the same quantity by two different routes.
The routes are worth distinguishing. The hectare is built by putting the prefix hecto in front of the are, so it is a hundred ares. The square hectometre is built by squaring a prefixed length, which is how the International System forms every derived area. The second construction is the strictly coherent one; the first is the one written on every land title in the world.
That difference explains where each name is found. Hectare appears in agriculture, forestry, planning, taxation and international statistics. Square hectometre appears mainly in technical and cartographic work in Spanish-speaking countries, where the hectometre is a familiar prefixed length for other reasons, and in documents where an author has chosen to keep every unit inside strict SI form.
The related cubic form is genuinely common in one field. Spanish and Latin American hydrology reports reservoir capacity and river flow in cubic hectometres, a cubic hectometre being one million cubic metres, so a reservoir holding 500 hm³ is holding half a cubic kilometre of water. Readers used to seeing hm in that context find hm² unremarkable, which is much of why the form survives there and almost nowhere else.
For scale, ten thousand square metres is a square one hundred metres on a side. That is about one and a half association football pitches, a large city block, or a good-sized field. It is the largest area that can still be walked around comfortably in a couple of minutes, and it is where land measurement stops being architectural and starts being agricultural.
When converting, the two names need no arithmetic between them: one square hectometre is one hectare exactly. Going further, multiply by ten thousand for square metres or divide by a hundred for square kilometres, and remember that the imperial comparison, 2.471 acres, is the same for both names.
One square hectometre equals 10,000 square metres, 1 hectare, 0.01 square kilometres, or about 2.471 acres.
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.