Credit Card Interest Calculator
What a balance costs to carry — per day, per month, and in total before it is cleared.
The address carries whatever you changed, so anyone opening it sees these numbers. Nothing is saved on our side.
Interest you will pay
$2,135
On top of the $5,000 you already owe, over 3 years. That is 42.7% of the balance, paid for the privilege of not clearing it now.
- $104.13
- 24.99% ÷ 12
- $3.42
- at today's balance
- $2,135
- $7,135
- 3 years
- $104.14
- a cent over the interest
What each payment costs in interest
Same balance, same rate, different monthly payment. The relationship is not linear — doubling the payment cuts the interest by far more than half.
| Monthly payment | Total interest | Total paid | vs yours |
|---|---|---|---|
| $100/moNever clears the balance | $0 | −$7,135 less in total | |
| $150/moCleared in 4 years 10 months | $3,622 | +$1,487 more in total | |
| $200/moyoursCleared in 3 years | $2,135 | — | |
| $300/moCleared in 1 year 9 months | $1,206 | −$930 less in total | |
| $500/moCleared in 1 year | $666 | −$1,469 less in total |
How the interest is actually charged
Three details that change the number on your statement, and are not in most calculators.
Daily, not monthly
Issuers apply a daily periodic rate to your average daily balance, then charge the total at the end of the cycle. This calculator uses a monthly rate, which is very slightly cheaper than the real method — a few dollars over a typical balance, and stated here rather than hidden.
The grace period
Pay the statement balance in full and new purchases are generally interest-free. Carry any balance and most issuers withdraw that grace period, so new purchases start accruing from the day they post. Interest on a card is closer to all-or-nothing than people expect.
Rates within one card
Purchases, cash advances and balance transfers usually carry different APRs on the same account, and cash advances typically have no grace period at all. This models one rate; if your balance is a mix, run the highest-rate portion separately.
How this calculator works
The same month-by-month engine as the Credit Card Payoff calculator, asked a different question.
Each month the balance accrues interest at the APR divided by twelve. Your payment covers that interest first; whatever is left reduces the balance. Repeat until it reaches zero, trimming the final payment so it lands exactly there.
A revolving balance has no closed-form answer the way an installment loan does, because what you owe next month depends on what you chose to pay this month. Simulating it is the only honest approach, and this page shares that simulation with the payoff calculator rather than reimplementing it — so the two pages cannot disagree about the same balance.
A payment at or below the first month’s interest is reported as never clearing the balance, rather than returned as a very large number of months. That is the most important thing a card calculator can tell someone, so it is stated plainly along with the smallest payment that would work.
What is assumed
- One APR on the whole balance, unchanged throughout.
- No new spending on the card.
- The same payment every month, on time.
- No annual fee, late fee or penalty rate.
A worked example
$5,000 at 24.99%, paying $200 a month.
| Monthly rate | 24.99% ÷ 12 |
|---|---|
| Interest in month one | $5,000 × 2.0825% |
| Of a $200 payment, to the balance | 200 − 104.13 |
| Cleared in | 36 months |
| Total paid | Over 36 months |
| Interest, on top of the $5,000 | 7,135.18 − 5,000 |
Just over half of the first payment does nothing at all. The interest is 42.7% of the amount borrowed by the time the balance clears — not an annual rate, an outright surcharge on the original $5,000 for taking three years to repay it.
Doubling the payment to $400 clears the same balance in 15 months for $852.71 of interest. Twice the payment, but the interest falls to 40% of what it was rather than to half — because each extra dollar cancels every future month of interest that dollar would otherwise have accrued.
Questions people ask
Issuers divide your APR by 365 to get a daily periodic rate, apply it to your average daily balance for the billing cycle, and charge the total on your statement. This calculator uses a monthly rate — APR divided by twelve — which is very slightly cheaper than the daily method. The difference is a few dollars on a typical balance, and it is stated here rather than buried.
Pay the statement balance in full by the due date every month. Do that and the grace period means purchases cost nothing to finance. Carry any balance, though, and most issuers withdraw the grace period, so new purchases start accruing interest from the day they post — and it usually takes two consecutive full payments to get it back. Card interest is closer to all-or-nothing than people expect.
Because interest is charged before your payment is applied to what you owe. At 24.99% a $5,000 balance accrues about $104 a month, so a $200 payment moves the balance by about $96 and the other $104 buys nothing. The result panel above shows this split for your own numbers — the first month's interest against your payment is the most useful pair of figures on this page.
No. Purchases, cash advances and balance transfers usually carry different APRs on the same account, and cash advances typically have no grace period, so they accrue from the moment you take the money. Most cards also carry a penalty APR that a late payment can trigger. If your balance is a mix, run the highest-rate portion separately.
Almost always the payment. Rate changes are incremental; payment changes are structural, because every extra dollar removes all the future interest that dollar would have accrued. The comparison table above holds your rate constant and varies only the payment, and the effect is nonlinear — doubling the payment cuts the interest by considerably more than half.
Yes, and it costs nothing to try. Issuers do reduce rates for customers with a good payment history, particularly on request. It is a phone call, and the worst outcome is no. Run your balance at the reduced rate above first, so you know what you are asking for in dollars rather than percentage points.
Related calculators
An estimate using monthly interest on the balance. Real issuers compute interest daily on an average daily balance, which costs slightly more. It models one APR; cash advances and transfers usually carry their own.