Why Revolving Card Interest Gets Expensive
Credit card interest is usually charged on balances that remain after the grace period is lost. Crucially, the interest-free grace period is lost entirely once you carry any balance from month to month, meaning new purchases start accruing interest immediately from the transaction date rather than after the next statement.
The calculator estimates monthly interest and applies your payment until the balance reaches zero. A higher APR or lower payment stretches the timeline and increases total interest. Note that this calculator uses monthly compounding as an approximation, whereas real credit cards typically compound interest daily (meaning the effective interest cost is slightly higher).
This page is best for one balance at a time. If you are comparing several cards and payoff order matters, use the Credit Cards Payoff Calculator instead.
Payment Size Is The Control Lever
The minimum payment may keep the account current, but it often does not reduce principal quickly. When APR is high, much of a small payment can be absorbed by interest.
Testing a larger monthly payment shows how much interest can be avoided by shortening the payoff period.
If the result barely moves even after payments, the balance may need a more aggressive plan, a lower-rate transfer, or spending changes that stop new charges.
Use The APR That Applies To The Balance
Use the purchase APR for ordinary carried purchases. Use the cash advance APR for cash advances and the balance-transfer APR for transferred balances when that rate applies.
Promotional rates should be tested twice: once at the promo APR and once at the regular APR after the promo ends.
Penalty APRs can be much higher, so missed payments can make the original estimate too optimistic.
New Purchases Can Break The Estimate
The calculator assumes the balance is being paid down without new purchases added to it.
If you keep using the card while carrying debt, new purchases may begin accruing interest and the payoff date can move further away.
For a clean payoff plan, many people freeze spending on the card and use cash, debit, or a separate paid-in-full card for current expenses.
Statement Details To Check
Check the current balance, statement balance, APR, minimum payment, and whether any promotional period is active.
If interest has already accrued but not posted, the next statement may be slightly different from the estimate.
Late fees, annual fees, and balance-transfer fees should be included only if they are part of the balance you will repay.
Interest Cost Scenarios To Run
Run the current payment first, then test a payment that is $50 or $100 higher.
Run the post-promo APR if the card has a teaser rate.
Run a no-new-purchases version and compare it with your real spending pattern before trusting the payoff date.
Credit Card Interest Cost Calculator FAQs
Why is the interest so high even with payments?
Because credit card APRs are often high and small payments reduce principal slowly. For example, at a 22% APR, about half of a typical minimum payment goes directly to interest rather than reducing the balance itself.
Should I enter the minimum payment?
Enter the amount you actually plan to pay each month, not only the required minimum unless that is your plan.
Does this include new purchases?
No. It assumes the balance is paid down without new charges.
Which APR should I use?
Use the APR that applies to the balance being repaid, including any post-promo rate if relevant. You can find your current APR on the first pages of your monthly billing statement, in your cardmember agreement, or inside your credit card issuer's online account or mobile app.
Is this the same as a payoff plan for several cards?
No. If you have several cards, use the Credit Cards Payoff Calculator to compare payment orders and build a multi-card plan.
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