An area is a length multiplied by a length. (A= l l as in the formula list.) An area is an amount of surface. Almost all area units are length units squared, such as: square meter (m2), square centimeter (cm2), square inch (in2), etc. The acre and hectare, units of land measurement, are the only units commonly used that are not in the "distance squared" area unit format. An acre is defined as 43,560 square feet, so in using the unit 'acre' in dimensional analysis, the definition can be used to relate the acre to other units. Notice the squaring of a unit of length. A meter multiplied by a meter is a square meter. A foot by a foot is a square foot, etc.