Use this calculator to determine the true, or average rate, weighted for the amount of each loan, over the life of the loan. The blended rate is the rate you are truly paying on the combined loans. If you can refinance the total of both loans into one new loan at a rate less then the blended rate, then you will be saving money. To allow for closing costs on the new loan, the new rate would need to be .25%, in general, lower than the current blended rate. For smaller loans the savings should be greater than .25%.