Area units conversion for metric and imperial measurement systems including several commonly used historical units.
In metric system (SI), the area unit (derived unit not a base unit) is square metre ("meter" is American spelling). Every length unit has a corresponding area unit and the area
is calculated by multiplying the length by the width.
The most common area units are hectare, acre, square meter, square centimeter, square kilometer, square inch, square feet, square yard and square mile.