The area of a parallelogram can be calculated by multiplying the length of the base by the height to the top, perpendicular to the base. Either edge on either set of sides can be oriented to be the base. The formula for a parallelogram's area is similar to that of a rectangle, because a rectangle is a special type of parallelogram.
For a two-dimensional shape to be considered a parallelogram, it must have four sides, with two pairs of equal sides. The opposite sides must be parallel from each other, and opposite angles must be equal. The perimeter can be calculated by measuring the length of the sides and adding them together.