View source for Weight Estimations

== Plywood ==

3 lbs/sqft per inch of thickness (APA Plywood Design Specification)


Example:

Length: 12 inches

Width: 12 inches

Thickness: 1/4 inches

144 sqin in a sqft


Formula: 

Weight = 3 lb * (L x W)/144 * T

Weight = 3 lb * (12 x 12)/144 * 0.25

Weight = 0.75 lbs


== Concrete ==

The weight of concrete differs based on the materials used. In some cases concrete is injected with materials to intentionally make it stronger, lighter, cure faster. Those variables may have an impact on the weight. for a rough estimation we'll use 145 lbs/ft3. Since our projects are rather small we will use the formula 145/12^3 so we have the lbs per cubic inch.

0.084lbs/cuin


Example:

I have a box I need to fill with concrete.

Length: 24"

Width: 12"

Height: 4"


Formula:

Weight = 0.084 * L * W * H

Weight = 0.084 * 24 * 12 * 4

Weight = 96lbs



== Sources ==
[[http://wiki.answers.com/Q/Weight_of_Plywood|http://wiki.answers.com/Q/Weight_of_Plywood]]