What is the standard purchase interest?
Standard purchase interest is simply the annual interest rate (APR) on your credit card.
You can check your standard purchase interest by contacting your credit card provider and if you want to know how your standard purchase interest works out to be your monthly interest charge on your credit card then simply divide your standard purchase interest by 12 or contact the credit card provider.
If you need financial advice and you live in the UK then you could contact the Money Advice service over the phone or via chat for impartial advice.
You can also contact the debt charity “Step Change” if you are in debt and need help.