Starting with the first line of entry fields, enter each of your debts, along with the corresponding principal balances, interest rates and monthly payment amounts. The last two columns will be filled in by the calculator. Once you have entered all of the debts you wish to consolidate, click on the "Compute Current Debt Cost" button. Next, enter the consolidating loan's interest rate, term and any origination fees that might apply and click the "Compute Consolidation Loan Costs" button. In order for the this calculator to work, each debt must have the four left-hand fields filled in (for interest-free debts enter .001 just to satisfy the required interest-rate entry). Also, be sure to enter only numbers and decimal points in the numeric entry fields. Dollar signs, percent signs, commas and spaces will cause an error.