A good strategy is to apply the concepts of the weighted average cost of capital (WACC). The WACC is essentially a blend of the cost of equity and the after-tax cost of debt. Therefore, we need to look at how cost of equity and cost of debt are calculated.
Discount rate is otherwise known as cost of capital and the term is used in capital budgeting. Most metrics such as NPV, MIRR, Profitability Index and Discounted Payback Period use this rate to discount the cash flows.
A good way to start is for you to look up WACC which stands for Weighted Average Cost of Capital and this is what you referred to as the discount rate.
It is made up of proportions of equities and debts which is multiplied by risk factors and finally summed up.
If you know what your total then the formula would be the following:
d= discount percent (in decimals)
t x (1 - d)
or if you want to just figure out the discount amount without the calculator automatically taking it out of the total, just do this:
T x d