Personal Finance Credit card interest rates: How to calculate interest rate on credit card Updated : July 16, 2019 11:53 AM IST All banks and financial institutions broadly calculate interest rates as an annual percentage rate (APR) which is the interest rate charged on the balance for a year. The State Bank of India charges up to 3.35 per cent per month and an APR of up to 40.2 per cent per annum. The interest rates are lower for secured card types, which are issued against collateral. Interest or finance charges are calculated on the pending amount for a particular bill cycle. Subscribe to Moneycontrol PRO at just Rs.33/- per month for the first year. Use code SUPERPRO. Limited period offer. Available on Web and Android.