3.33%。 The mortgage interest rate is usually expressed as a percentage, and the mortgage interest rate refers to the monthly interest rate. The formula for converting the annual interest rate into the monthly interest rate is that the monthly interest rate is equal to the annual interest rate divided by 12. According to the benchmark lending rate of the central bank (the one-year lending rate is 4.0%), the monthly interest rate is converted into 4% divided by 12, which is about 0.333%, that is, 3.33%.