Interest has a very complicated calculation formula, which will be unclear for a while. Repayment methods are divided into two algorithms: equal principal and interest and average principal. You can download an interest rate calculation software, there should be many online, enter the principal, years, interest rate, and you can calculate the monthly payment. There are two kinds of questions about the annual interest rate, one is to sign the contract once a year, and the other is to fix the interest rate. Generally, when a bank signs a contract for you, it changes every year, that is, at the beginning of each year, the latest interest rate of the previous year is used to calculate the monthly repayment amount of the next year. Perhaps for this reason, the central bank raised interest rates at the end of last year. I guessed, haha. The average capital starts with a high repayment rate and decreases slightly month by month. Matching principal and interest, the monthly repayment amount is fixed for one year. During the whole repayment period of average capital (for example, 30 years), the total interest payment is less than other methods. This requires you to weigh the pros and cons from two aspects.