Generally speaking, buying a house is divided into two situations, the calculation formula is: 1, and the average capital repayment method is: quarterly repayment amount = loan principal ÷ quarterly number of loan term+(principal-accumulated amount of repaid principal) × quarterly interest rate; 2. repayment method of equal principal and interest: monthly repayment amount = [loan principal × monthly interest rate ×( 1+ monthly interest rate) ÷ repayment months ]÷[( 1+ monthly interest rate) × repayment months-1].

Legal basis: Article 27 of the Implementation Measures for Post-loan Evaluation of the People's Construction Bank of China.

Loan repayment evaluation. Mainly analyze the interest payment rate, loan repayment period and loan repayment rate due. (1) Interest yield refers to the ratio of the accumulated amount of interest actually collected at maturity to the accumulated amount of interest receivable at maturity. The calculation formula is as follows: the actual paid-in rate of accumulated interest due =-100% of accumulated interest due; (2) The loan repayment rate at maturity refers to the ratio of the amount actually repaid by the borrower to the amount that should be repaid according to the loan contract from the time when the borrower invested in the post-evaluation. The calculation formula is as follows: Accumulated repaid loan amount due, and loan repayment rate due =-100% loan amount due. When the interest payment rate is equal to 1, it indicates that the borrower has repaid the loan principal and interest as agreed in the loan contract; When the interest payment rate and the loan repayment rate due are less than 1, it indicates that the borrower has not fully repaid the loan principal and interest as agreed in the loan contract. Therefore, risk analysis should be carried out to explain the source of risk, whether there are methods to eliminate or transfer risk, and the implementation of the original guarantee. (3) loan repayment period. It refers to the time required to repay fixed assets investment loans with repayable profits, depreciation and other income after the project is put into production under the current national fiscal and taxation system and the specific financial situation of the project. Post-evaluation loan repayment period is generally calculated by tabular method. See the loan repayment period calculation table (evaluation table 6). When evaluating the calculated repayment period, we should compare the estimated repayment period with the repayment period calculated at the time of evaluation and the repayment period determined in the loan contract, and analyze whether the borrower can repay the loan of China Construction Bank on schedule. If the loan cannot be repaid on time, the reasons should be analyzed and the countermeasures and suggestions for speeding up the loan recovery should be put forward.