The U.S. prime rate is the national prime rate as published by the Wall Street Journal. It’s based on the prime rates from the nation’s largest banks. Many variable interest rate credit cards based their rates on the U.S. prime rate For example, the APR on a credit card might be the prime rate plus 13%. If the prime rate is 3.25%, the current APR on that variable rate card would be 16.25%.
Your credit card interest rate will follow the movement of the prime rate. If the prime rate goes up, you can expect your credit card interest rate will soon go up. On the other hand, if the prime rate goes down, your credit card interest rate should go down. Credit card issuers don’t have to give advance notice of interest rate changes if you have a variable interest rate.
The U.S. prime rate is usually about 3% higher than the federal funds rate and is available at the Wall Street Journal's website.