<prompt> Human: I am looking at an amortization schedule for a loan. If I prepay principal, does it reduce interest expense anywhere? Does it apply principal to the end of the schedule? How does it work?Thank you!edit: can you make a new amortization schedule after prepayment to come up with the same numbers based on whatever principal is leftover?Assistant: Your monthly payment is calculated based on a formula that takes the number of payments, the interest payment and the amount due.Your monthly interest payment is based solely on how much money is left in the loan and your apr. If you an a friend have the same balance and the same interest rate, you will pay the same amount in interest that month, no matter the age or term of the loan. The remaining money will go to principal.If you pay more principal, your interest, which is calculated on your current balance, will go down accordingly.Heres instructions how to make an custom calculator in excel. Using this template and doing it myself helped me understand.Human: So if I pay extra principal payments my monthly payment will decrease?? Because I will owe less interest?  <response>: From my experience with my mortgage, the monthly payment does not go down, it just means the loan will be paid off sooner. 