After deferred repayment of Ping An Credit Card for 3 days, the bank will charge interest. The bank calculates interest based on the number of days the payment is deferred and the amount owed.

Specifically, the interest charged by the bank is calculated as follows:

1. Number of days of deferred repayment: Banks usually calculate a year as 360 days, so a 3-day deferred repayment means The interest calculation period is 3/360.

2. Amount owed: Banks usually calculate interest based on the daily balance owed. Assume that the amount owed before deferred repayment is X yuan, then the basis for calculating interest is X yuan.

3. Annual interest rate: The bank will give a certain annual interest rate, such as 5%. This annual interest rate will be used to calculate daily interest.

By combining these factors, the bank can calculate the interest for a three-day delay in repayment. The specific calculation formula is:

Interest = Amount owed × annual interest rate × number of days of deferred repayment

To sum up, the bank will charge interest after 3 days of deferred repayment on a credit card. Interest is calculated based on the amount owed, the annual interest rate and the number of days in arrears. Banks usually calculate interest based on a 360-day year.

Extended information: Credit card deferred repayment refers to repayment within a certain period of time after the repayment date. Generally speaking, banks will grant a certain grace period, but delayed repayment will accrue interest. Therefore, to avoid incurring additional charges, it is recommended to repay your loan on time.

Note: The above answers are for reference only, and the actual calculation method may differ due to bank policies and contract terms. It is recommended to check the relevant contracts and policies when actually using the credit card to understand the specific interest calculation rules.