Most lending institutions charge penalty interest at 130%-150% of the contracted interest rate. For example, the overdue principal and interest of a loan is 3,000 yuan, and the loan interest rate is 4.9%. Based on the minimum penalty interest calculation, the penalty interest for one day the loan is overdue is 3,000 × (4.9% ÷ 365 × 130%) × 1 = 0.52 yuan.

Legal basis: Article 671 of the Civil Code If the lender fails to provide the loan in accordance with the agreed date and amount, causing losses to the borrower, it shall compensate for the losses. If the borrower fails to collect the loan on the agreed date and amount, the borrower shall pay interest on the agreed date and amount.