Debt
Credit Card Interest Calculator
Credit card interest is the quiet tax on carrying a balance. Enter your balance, APR, and the payment you can actually make — and see how long the card takes to die, how much interest it charges you for the privilege, and what share of every payment never touches the debt.
Results
Payoff time: 4 years 10 months, Total interest: $3,622.26, Total repayment: $8,622.26, Interest share of payments: 42%
- Payoff time
- 4 years 10 months
- 58 payments at this amount
- Total interest
- $3,622.26
- Total repayment
- $8,622.26
- Interest share of payments
- 42%
- Of every dollar you repay, this part is interest
Milestones
| Milestone | |
|---|---|
| First month’s interest charge | $104.13 |
| Balance after 12 payments | $4,381.86 |
| Balance after 24 payments | $3,590.25 |
| Final payment amount | $72.26 |
- Actual credit card issuers typically calculate interest using the daily periodic rate (APR ÷ 365) on your average daily balance, compounded daily — contractual details vary by issuer.
- This projection assumes no new purchases on the card; in reality, new spending extends the timeline.
- Paying the full statement balance each month avoids interest entirely (grace period) — this tool models carrying a balance.
How to use this calculator
- Enter your current balance as shown on your statement.
- Enter your purchase APR — for cards with promotional rates, enter the rate that applies after the promo ends, because that is what will dominate the timeline.
- Enter the monthly payment you can commit to. Anything above the minimum accelerates everything.
- Read the interest share KPI: it tells you how many cents of every dollar you pay are interest rather than debt.
- Compare with the Debt Payoff Calculator if you hold several cards — extra dollars belong on the highest APR first.
How the calculation works
monthly interest = balance × APR ÷ 12 principal paid = payment − monthly interest
The simulation charges interest monthly on the unpaid balance and splits each payment between interest and principal. This is the standard approximation used across the industry; your issuer’s exact method differs (see the note below) but produces very similar results.
Worked example
Input
Balance $5,000 at 24.99% APR, paying $150 per month (well above a typical ~$130 minimum).
Result
Payoff in 58 months (nearly 5 years), $3,622 total interest, $8,622 total repayment — interest alone is 72% of the original balance. Paying $250 instead clears it in 27 months with about $1,535 interest.
Assumptions and important notes
- Actual credit card issuers may calculate interest using the daily periodic balance (APR ÷ 365 applied to your average daily balance, compounded daily) and other contractual rules — this calculator uses the close monthly equivalent.
- No new purchases are added to the balance during the payoff.
- The APR stays constant; promotional rates, penalty APRs, and annual fees are not modeled.
- Payments are made on the same day each month.
Frequently asked questions
How is credit card interest actually calculated?
Most issuers divide your APR by 365 to get a daily periodic rate, apply it to your average daily balance each day of the billing cycle, and compound. If you pay your statement balance in full every month, a grace period usually means you pay zero interest at all. This calculator’s monthly model (APR ÷ 12 on the unpaid balance) tracks the daily method within rounding for payoff planning.
Why is the minimum payment so dangerous?
Minimums are often about 1% of the balance plus interest — designed to keep you paying for decades. On the example above, a minimum-style payment barely dents the balance each month; nearly all of it is interest. If your entered payment is ever below one month’s interest, this calculator will tell you the debt can never be paid off at that amount.
What payment makes the biggest difference?
The first dollars above the minimum are the most powerful you will ever send: at high APRs, going from the minimum to a fixed $150–$300 often cuts the timeline by more than half. Use the calculator to find the payment level where the payoff date suddenly feels real, and lock that in as an autopay amount.
Should I transfer the balance to a 0% card instead?
A 0% balance transfer can pause interest for 12–21 months (usually for a 3–5% fee), and this calculator doubles as a transfer sanity check: run it with APR 0 and your planned payment — if you cannot clear the balance inside the promo window, you will owe the regular rate on whatever remains, plus the fee you already paid.
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