Though the term "oblong" might seem strange, its shape is quite familiar. An oblong is just a particular type of rectangle, which is a parallelogram with 90-degree angles. Where a typical rectangle has no rules governing its dimensions of length and width, an oblong rectangle always has one greater than the other. This means that though a normal rectangle can have equal sides and be a square, an oblong rectangle cannot. Area calculation of an oblong follows the same formula as other rectangles, where area equals length times width.

Obtain the rectangle's width. For this example, let the width be 15.

Obtain the rectangle's length. For this example, let the length be 30.

Multiply the rectangle's measurements together. For this example, multiplication of 15 and 30 results in 450.