What this calculator returns
Enter Current card balance ($), Annual percentage rate, APR (%), Minimum payment per month ($), and, if needed, Extra payment per month ($, optional). The calculator returns months to payoff, total interest, total payments, the monthly payment used, the calculation formula, assumptions, and a full month-by-month schedule.
How to use the calculator
- Enter the four visible values. Leave Extra payment per month ($, optional) blank or enter a non-negative amount.
- Click Calculate to display the result and schedule.
- After a valid result appears, click Copy result or Download result (.txt).
- Click Reset to clear all four inputs, hide errors, and hide the result.
How the monthly calculation works
The calculator converts the APR to a monthly rate with APR / 100 / 12. Each month, it calculates interest from the remaining balance:
Interest = Remaining balance x monthly ratePrincipal = (Minimum payment + Extra payment) - InterestRemaining balance = Remaining balance - Principal
The combined payment covers that month's interest first. The remainder reduces principal. The regular payment is used until the final month; then the script adjusts the payment to the exact remaining balance plus that month's interest, so the final payment may be lower. Total interest is the sum of each month's interest.
How to read the result
The headline results show months to payoff, total interest paid, total of all payments, and total monthly payment used. The assumptions table lists intermediate values.
The schedule columns are Month, Payment, Principal, Interest, and Remaining balance. Year-end rows are shaded. The schedule scrolls vertically, with horizontal scrolling available on narrow layouts.
Extra-payment comparison
The calculator adds Extra payment per month ($, optional) to the minimum payment. Comparison statistics appear only when the extra payment is greater than zero, the minimum payment alone exceeds the first month's interest, and the minimum-only schedule finishes within the 100-year simulation ceiling. When available, the result reports interest saved and time saved versus minimum-only. These statistics are omitted if the minimum-only schedule does not meet those conditions.
Validation and calculation assumptions
- The balance must be greater than 0.
- APR must be between 0 and 100.
- Minimum payment must be greater than 0.
- Extra payment must be 0 or greater when entered.
- The combined payment must exceed the first month's interest.
- The simulation must finish within 100 years.
- The model assumes a fixed APR and regular monthly payment, with the final payment adjusted to the remaining balance plus that month's interest. It includes no new purchases, cash advances, balance transfers, fees, promotional rates, penalty APRs, or missed payments.
- Money is displayed to two decimal places, while the calculation retains JavaScript numeric precision internally.
What the calculator does not use or provide
The calculator uses only the values you enter. It does not fetch live rates, card issuer records, credit data, or account data. Its APR / 100 / 12 monthly model is a mathematical estimate, not an official card issuer payoff quote or personalized financial advice. Compare the result with your issuer's statement calculation.
Privacy and calculation scope
The payoff calculation uses your inputs in the browser, and this calculator workflow does not submit those calculator values. This statement applies to the calculator inputs; the page also contains other site features, such as a separate subscription form.
Frequently Asked Questions
How is the monthly interest on a credit card calculated?
Monthly interest = Remaining balance x (APR / 100 / 12). The APR is divided by 12 to get a monthly periodic rate, which is applied to the current balance each month before that month's payment is applied.
How is the payoff schedule built month by month?
Each month: Interest = Remaining balance x monthly rate. Principal = (Minimum payment + Extra payment) - Interest. Remaining balance = Remaining balance - Principal. This repeats until the remaining balance reaches zero, and every month's interest is summed for the total interest figure.
What happens if my minimum payment doesn't cover the interest?
If the minimum payment plus extra payment is less than or equal to the first month's interest charge, the balance cannot shrink and would grow indefinitely. The calculator detects this and shows an error instead of a result, asking for a higher payment.
What does the extra payment comparison show?
When an extra payment is entered, the calculator can also run the same balance and APR with the minimum payment alone. It reports the interest and time saved only when that minimum-only schedule exceeds the first month's interest and finishes within 100 years.
Does this tool use my actual card or account data?
No. It only uses the balance, APR, minimum payment, and extra payment you type in. It does not fetch live interest rates, credit records, or any card issuer or account data, and it is not personalized financial advice.