area (A)
Area (symbolized A ) is a two-dimensional quantity representing amount or extent of surface. The standard unit of area in the International System of Units ( SI ) is the meter squared (m 2 ).
Area is usually measured or defined on a flat surface, also called a Euclidean plane, or on a spherical surface. For example, we might speak of the area of a parcel of land, the cross-sectional area of a fiber optic cable, or the surface area of the earth. But surface area is occasionally determined for irregular objects. In the case of certain extremely complex or esoteric surfaces, the area might be impossible to define or measure. One example is a mathematical object having a fractional number of dimensions. Another example is an object without a well-defined surface.
When expressing large or small areas, prefix multiplier s are attached to the meter squared. The table below shows the most common alternative area units and their relationship to the meter squared.
| Unit (and symbol) |
To convert to meters squared, multiply by: |
Conversely, multiply by: |
| kilometer squared (km 2 ) | 10 6 | 10 -6 |
| centimeter squared (cm 2 ) | 10 -4 | 10 4 |
| millimeter squared (mm 2 ) | 10 -6 | 10 6 |
| circular mil | 5.066 x 10 -10 | 1.974 x 10 9 |
| foot squared (ft 2 ) | 0.0929 | 10.76 |
| micrometer squared or micron squared (µ 2 ) |
10 -12 | 10 12 |
| nanometer squared (nm 2 ) | 10 -18 | 10 18 |
| Angström squared (Ä 2 ) | 10 -20 | 10 20 |
Compare displacement and volume . Also see meter squared , centimeter squared , foot squared , circular mil , International System of Units ( SI ), and Table of Physical Units .