Questions: Cost calculations

[Angelo]

Is it possible to make a calculation with the field "time estimated" and an hourly rate to arrive at a "estimated cost" which is in project planning a blocking issue as you know. At the moment calculation has to be done by calculator and put in the field "cost" resulting in wrong figures when "estimated time" changes and "cost" is not recalculated with the machine.
many, many thanks for taking in consideration.