At present, the loan interest of rural credit cooperatives is usually calculated by product method according to the actual loan days. Generally, there are two situations: normal interest calculation and overdue interest calculation. The first one is: interest = principal * interest rate. * Actual loan days (it can be counted as the beginning and end, which varies from place to place). The interest rate is generally determined by the credit cooperatives within 2.3 times of the national listed loan interest rate (allowed by the state). % is the annual interest rate and ‰ is the monthly interest rate. For example, if someone borrows RMB 65,438+10,000 on March 1 day, the loan interest rate is 10.5‰, and the maturity date is May 30, and it is agreed to repay the principal and interest in one lump sum, then the interest payable on the maturity date of the customer is: principal 65,438+10,000 * day interest rate (10.5 ‰/30 If it is overdue, you can add overdue interest. If it is agreed to collect interest on a monthly basis, you can impose a penalty interest on the interest that is not collected on a monthly basis.