Glad you asked...
There are a couple of different ways to calculate psi, or pounds per square inch. One of these ways is based on weight and area of an item. Click here for more info http://www.engineersedge.com/wwwboard/po...
Then again, this answer might help you...
The proper formula for PSI is PSI= F/A. The conversion factor for converting anything to PSI is to multiply the unit measurement by 0.5.

