What is the equation for calculating the default risk premium?

A risk premium is the minimum difference between the expected value of an uncertain bet that a person is willing to take and the certain value that he is indifferent to.

I believe he asked for the formula not the dictionary definition.

As far as I know there isn't one. The closest I've ever gotten is:

http://gaap.cz/main_page/obrazky/Image1.jpg

Who has the simplest way to calculate the default risk premium, given the yield, real rate of return, inflation premium, liquidity premium, & maturity risk premium with a financial calclator?

risk premium= Km - Krf