Down Payment Calculator (12a) Rate of Return on Larger Down Payment Who This Calculator is For: Borrowers with enough cash to make a down payment in excess of the minimum required on a particular loan, who want to know whether using the cash to increase the down payment earns a high rate of return. What This Calculator Does: This calculator allows you to determine the rate of return on an investment in a larger down payment that reduces or eliminates mortgage insurance, and that might reduce the interest rate.