The contract law stipulates that the loan interest rate shall not violate the provisions of the state on limiting the loan interest rate; Judicial interpretation specifically stipulates that the maximum agreed interest rate shall not exceed four times the interest rate of similar loans of banks. This means that the interest rate of private lending should not exceed 4 times of the bank loan interest rate in the same period, and both parties can negotiate within 4 times of the bank loan interest rate in the same period.
From this, it can be concluded that the loan interest rate within 4 times of the bank's loan interest rate in the same period belongs to the legal interest rate, and the loan interest rate over 4 times belongs to usury, and the usury part is not protected by law.