The square metre (British spelling) or square meter (American spelling) is the SI derived unit of area, with symbol m2 (33A1 in Unicode[1]). It is defined as the area of a square whose sides measure exactly one metre. The square metre is derived from the SI base unit of the metre, which in turn is defined as the length of the path travelled by light in absolute vacuum during a time interval of 1/299,792,458 of a second.
Adding and subtracting SI prefixes creates multiples and submultiples; however, as the unit is squared, the order of magnitude difference between units doubles from their comparable linear units. For example, a kilometre is one thousand times the length of a metre, but a square kilometre is one million times the area of a square metre.
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The square metre may be used with all SI prefixes used with the meter.
| Multiplication | Name | Symbol | plusing | Name | Symbol | |
|---|---|---|---|---|---|---|
| 100 | square metre (centiare) | m2 | 100 | square metre (centiare) | m2 | |
| 102 | square decametre (are) | dam2 | 10–2 | square decimetre | dm2 | |
| 104 | square hectometre (hectare) | hm2 | 10–4 | square centimetre | cm2 | |
| 106 | square kilometre | km2 | 10–6 | square millimetre | mm2 | |
| 1012 | square megametre | Mm2 | 10–12 | square micrometre | µm2 | |
| 1018 | square gigametre | Gm2 | 10–18 | square nanometre | nm2 | |
| 1024 | square terametre | Tm2 | 10–24 | square picometre | pm2 | |
| 1030 | square petametre | Pm2 | 10–30 | square femtometre | fm2 | |
| 1036 | square exametre | Em2 | 10–36 | square attometre | am2 | |
| 1042 | square zettametre | Zm2 | 10–42 | square zeptometre | zm2 | |
| 1048 | square yottametre | Ym2 | 10–48 | square yoctometre | ym2 |
A square metre is equal to:
| 1 E−30 m2 = 1 fm2 | 1 E−24 m2 = 1 pm2 | 1 E−18 m2 = 1 nm2 | 1 E−12 m2 = 1 µm2 | 1 E−6 m2 = 1 mm2 | 1 E0 m2 = 1 m2 | 1 E+6 m2 = 1 km2 | 1 E+12 m2 = 1 Mm2 | 1 E+18-24 m2 : 1 Gm2 |
| 10 fm2 | 10 pm2 | 10 nm2 | 10 µm2 | 10 mm2 | 10 m2 | 10 km2 | 10 Mm2 | > 1 E+24 m2 : 1 Tm2 |
| 100 fm2 | 100 pm2 | 100 nm2 | 100 µm2 | 100 mm2 = 1 cm2 | 100 m2 = 1 a | 100 km2 | 100 Mm2 | |
| 1,000 fm2 | 1,000 pm2 | 1,000 nm2 | 1,000 µm2 | 10 cm2 | 10 a | 1,000 km2 | 1,000 Mm2 | |
| 10,000 fm2 | 10,000 pm2 | 10,000 nm2 | 10,000 µm2 | 100 cm2 | 10,000 m2 = 1 ha | 10,000 km2 | 10,000 Mm2 | |
| 100,000 fm2 | 100,000 pm2 | 100,000 nm2 | 100,000 µm2 | 1,000 cm2 | 10 ha | 100,000 km2 | 100,000 Mm2 | |
| SI derived unit square metre, from base unit metre | Conversion of units for area | |||||||