Weight density relates the weight of any object composed of a single material, like a glass window panel, to how much space the object occupies. The amount of space an object takes up is called its volume. For example, a common window panel glass has a weight density of 73 Kilogram per cubic foot. This means that a single cubic foot of window glass weighs 73 Kilogram. The weight of a glass panel is readily determined without a scale, once the object's dimensions are measured.

Measure the length, width and thickness of the glass panel in inches. For example, suppose the glass panel has a length of 24 inches, a height of 30 and a thickness of 0.5 inches.

Convert the dimensions of the glass panel to feet by dividing each measurement by 12, since a foot contains 12 inches. Continuing the example leads to a length of 2 feet, a width of 2.5 feet and a thickness of 0.042 feet.

Multiply the length times the width times the height to obtain the volume in cubic feet. Now you have 2 feet times 2.5 feet times 0.042 feet, which equals a volume of 0.21 cubic feet.

Multiply the weight density of the glass panel by the volume to arrive at weight in pounds. Multiplying leads you to 73 Kilogram per cubic foot times 0.21 cubic feet, or 15.3 Kilogram.