The worksheet this page can reproduce
The CFPB's building-block worksheet follows a $300.00 card charge at a 23 percent APR. It says that APR is 1.92 percent on a monthly basis, and that the contract requires a $15.00 minimum whenever a balance remains. Twenty-three divided by twelve is 1.9166… percent, which rounds to 1.92 percent. Interest each month is the balance times 0.0192, rounded half-up to the cent, then the $15.00 comes off. The published ending balances for the first seven months are $290.76, $281.34, $271.74, $261.96, $251.99, $241.83, and $231.47. This calculator matches those seven figures, and it matches the eighth month's interest of $4.44.
The worksheet prints an eighth ending balance of $220.92. The line it prints is $231.47 plus $4.44 minus $15.00, and that addition is $220.91. This page uses the addition, so month eight ends at $220.91. The rest of the schedule continues, at the same monthly rate, until the balance is zero. On these inputs that takes 26 months and $82.14 of interest. The minimum in the story never changes. A real minimum often falls as the balance falls, or it hits a floor. Type the payment you will send, not a minimum the page invents.
Daily interest is the more common issuer method
The CFPB's question on card interest says many companies calculate interest daily from the average daily balance. The daily periodic rate is the APR divided by 365, or sometimes by 360, depending on the agreement this page has not read. Because interest accrues daily, paying earlier in the cycle reduces the interest if there is no grace period. A monthly model cannot see the day you pay. It is the right model for checking the worksheet and the wrong model for reproducing a statement that uses average daily balance. If your statement and this page disagree, the statement is the one attached to the account.
A grace period, when the card has one, changes the question. The CFPB says you can avoid interest on purchases if you pay the full balance by the due date. This tool still runs the monthly interest formula. If the payment you type clears the balance in the first month, the interest is only that month's charge, or zero if you are modeling a grace period by not revolving. The page does not know whether your card has a grace period. Paying more than the minimum and less than the full balance is also covered by the CFPB's rule that the amount above the minimum generally goes to the highest-rate balance first. This page has one rate. It cannot split a payment across a purchase balance and a cash-advance balance.
Minimums are not a payoff plan
The worksheet's point is visible in the first eight months: $15.00 on $300.00 at that rate removes only a few dollars of principal after interest. The balance is still $220.91 after eight payments. Paying more than the minimum shortens the schedule and cuts the interest. The loan payoff page does the same kind of comparison for an installment loan, with the site's other interest rounding. A card is not an installment loan. There is no contractual term that forces the balance to zero. The term is whatever your payment produces. If the payment does not cover interest, the balance would rise, and this page stops instead of showing a balance that grows.
Moving a card balance onto a home equity line is a different risk. The CFPB's home-loan toolkit says counselors caution against using a HELOC to wipe out card debt, because the home secures the new debt. The HELOC page will show an interest-only payment. It will not tell you to do that transfer. Compare the rates yourself if you want the arithmetic, and remember that a lower rate secured by the house is not the same product as an unsecured card.
A payoff quote is still the issuer's number
The months here assume the APR never changes and the payment arrives every month in the same amount. A penalty APR, a returned payment, or a new purchase starts a different balance. The CFPB's interest answer also says cash advances and checks drawn on the card can carry different rates from purchases. If you revolve more than one rate, the single APR in this form is an average you would have to choose, and the page will not choose it. Pay the statement off during a grace period and the interest in this model is the wrong story, because the grace period can erase purchase interest the monthly formula still computes.
What you should type
Type the statement balance you are trying to clear, the purchase APR if that is the balance you mean, and the dollars you will pay every month. Do not type a promotional rate unless that rate will actually last for the whole payoff. A rate that jumps later is two schedules, and this page runs one. Do not type the minimum if you plan to pay more. The months and the interest are only as steady as the payment.
Giuseppe Ilarda, the site owner, writes and checks the schedule. It is an educational estimate of one monthly method. It is not financial advice, not a payoff quote from the issuer, and not a statement of the interest you have already been billed. The disclaimer covers that limit. The editorial policy is where the installment-loan rounding lives. This card method is separate, and it is documented as the worksheet's monthly rate so the published rows can be checked.