While the exact formula for calculating the number of months to pay off a credit card can be complex due to varying interest calculation methods, a simplified approach for a fixed monthly payment (P) on an outstanding balance (B) with a monthly interest rate (i) is often based on the amortization formula. However, for credit cards, it's more about iteratively reducing the balance:
Monthly Interest = (Outstanding Balance × APR) / 12
Principal Paid = Monthly Payment - Monthly Interest
New Balance = Outstanding Balance - Principal Paid
This process repeats each month until the balance is zero.