For the purchase of real estate, either a commercial property to gain rental income or a home to live in, mortgage loans are often needed. The percentage of down payment to loan amount can vary. Often this is a 40% down payment with a 60% loan for commercial property. And a 20% down payment with a 80% loan for a home to live in. Here is a mortgage calculator to help figure out the monthly payments. The interest rate and years for the loan can vary.