Sorry, but there is no exact way to tell. The conversion factor that was used in the previous post is for converting pounds of water into the number of cubic feet of water. Topsoil has a different density than water, thus rendering the conversion wrong. Different types of topsoil would have different densities, and even the same type of topsoil could have different densities (compacted and loose). What I am getting at is there is no exact way to determine this using a conversion factor. Around here, the general rule is that a ton of topsoil equals about a cu yard, but this is a very general rule.
I just found this in my Pocket Ref. It lists "Earth, Loam, Dry, Excavated" as having 78 lb. per cu. ft. That works out to: 40 lb/78 = .52 cu. ft. Still, this is an estimate, and to me it seems very low.
Eric
[Edited by eskals on 01-16-2001 at 01:51 PM]