One of the problems many people have when considering a compactor or densifier for scrap foam plastics is how much foam do they really have? Since packaging foam is very lightweight and can be very bulky, what appears to be a large quantity may not be so much after all. Typical polystyrene foam packaging and insulation is usually in the density range of 1 to 2 pound per cubic foot. What this means is if you have a 12 inch x 12 inch x 12 inch cube of solid foam, it would weigh between 1 and 2 pounds. Since most packaging foam is not used in a solid block form but is molded into relatively thin designs to protect the product, several cubic feet of polystyrene or polyethylene packaging foam may be required to equal a pound of foam.
Here are a few guidelines for estimating the weight of uncompressed EPS or EPE foam pieces. (This excludes stacked sheet foam and block foam)