How Credit Card Interest Works
Credit card interest is calculated using your Annual Percentage Rate (APR), but it compounds daily rather than monthly. Your issuer converts your APR into a daily periodic rate by dividing it by 365 (or sometimes 360). Each day, interest accrues on your average daily balance. At the end of the billing cycle, those daily charges are added together and appear on your statement as your monthly finance charge.
This daily compounding means you pay interest on interest. If you carry a balance from month to month, new purchases and existing debt both generate daily charges. Paying your statement balance in full by the due date eliminates interest entirely — the grace period is one of the most valuable features of credit cards when used responsibly.
When you only make partial payments, the remaining balance continues accruing interest every single day. At the Federal Reserve G.19 average of 22.36% APR for accounts assessed interest (August 2026), every $1,000 carried for a month costs about $19 in simple monthly interest before compounding — which is why revolving balances are among the most expensive consumer debt you can carry.
Source Federal Reserve G.19 Consumer Credit (Aug. 2026 data, released Oct. 7, 2026). Checked October 2026. We quote the G.19 “accounts assessed interest” rate (22.36%), not the 21.19% average across all accounts (including paid-in-full balances).
Minimum Payment Formula (What This Calculator Uses)
Issuers use several minimum formulas; this calculator models a common one printed in cardmember agreements: the greater of $25 or the month's interest plus 1% of the balance. You can change the 1% in the calculator. Each month:
Interest = balance × (APR ÷ 12); minimum payment = max($25, interest + 1% × balance); principal reduction = payment − interest. Because the minimum always exceeds the month's interest, the balance falls every month, but slowly: the principal share is only 1% of the balance.
On the default $8,000 balance at 22.36% APR, the first minimum is $229: about $149 of interest plus $80 (1% of $8,000) toward principal, so roughly 35% of the payment reduces the debt. As the balance shrinks the minimum shrinks with it, and the $25 floor takes over once the balance is below about $870. Paying only the minimum takes about 278 months (23 years) and about $13,831 in interest, versus 50 months and $4,282 in interest at a fixed $250 per month.
Source Chase cardmember agreement on file with the CFPB (minimum payment: larger of $25 or 1% of the new balance plus interest and late fees). Checked October 2026. Your own formula is in your cardmember agreement and on each statement; flat-percentage and fee-inclusive formulas change the timeline.
The Minimum Payment Trap
A common minimum-payment formula is the larger of a flat $25 or 1% of the balance plus that month's interest and any late fees. That keeps the payment small relative to the debt: at 22.36% APR, interest alone takes about 65% of the first payment on an $8,000 balance, and the minimum falls as the balance falls, so the payoff drags on for decades.
Use our calculator above to compare minimum-only payments against a fixed monthly payment at the same APR. On $8,000 at 22.36%, the fixed $250/month path in the default inputs pays off in 50 months with about $4,282 in interest. The minimum-only path takes about 278 months and about $13,831 in interest, so the fixed payment saves about $9,549 and 228 months (19 years).
Case Study: Sarah's $12,000 Credit Card Debt
Sarah accumulated $12,000 in credit card debt across two cards near the G.19 assessed-interest average (22.36% APR). Her combined minimums started around $344 per month: about $224 of interest plus $120 (1% of the balance) toward principal. Running the numbers at 22.36% with the interest-plus-1% minimum model, paying only minimums would take about 318 months (26.5 years) and cost about $21,285 in interest.
Sarah cut discretionary spending and committed to a fixed $400 monthly payment instead, only about $56 above her starting minimum. At 22.36% APR, that clears $12,000 in about 45 months with roughly $5,739 in total interest, saving about $15,500 in interest and 273 months (22 years and 9 months) compared with paying only the minimum.
Strategies to Pay Off Credit Card Debt Faster
Once you understand the cost of minimum payments, list every card, its balance, APR, and minimum payment. Then choose an approach that fits your situation.
- Pay more than the minimum: Even an extra $50 to $100 per month significantly reduces total interest and payoff time.
- Use the avalanche method: Pay minimums on all cards, then direct extra money to the highest APR card first. Read our guide on Debt Avalanche vs Snowball for a full comparison.
- Stop adding new charges: Put the cards away and use cash or debit until the balance is gone.
- Automate your payments: Set up automatic transfers for your target payment amount so you never accidentally pay only the minimum.
- Apply windfalls to debt: Tax refunds, bonuses, and side income applied to principal can shave months off high-APR balances.
For a multi-debt payoff plan, use our Debt Payoff Calculator to model extra payments across several accounts.
Payoff Timelines at Different Payment Levels
Estimated timelines for a $12,000 balance at 22.36% APR (interest plus 1% minimum model with a $25 floor for the minimum row; fixed payments otherwise). No new purchases.
| Monthly Payment | Months to Pay Off | Total Interest | Total Cost |
|---|---|---|---|
| $344 (interest + 1% minimum start, falling) | 318 | ~$21,285 | ~$33,285 |
| $250 fixed | 122 | ~$18,443 | ~$30,443 |
| $400 fixed | 45 | ~$5,739 | ~$17,739 |
| $600 fixed | 26 | ~$3,155 | ~$15,155 |
Going from $250 to $400 per month cuts the timeline from 122 months to 45 months and saves about $12,700 in interest on this balance.
Balance Transfer vs Payoff Strategies
A balance transfer moves debt to a card with a 0% introductory APR for 12 to 21 months. Transfer $8,000 into an 18-month 0% offer and you need about $445 per month to clear the balance before the promo APR ends. Watch transfer fees (often 3% to 5%) and avoid running up the old card again.
For most people, increasing fixed payments on existing cards is the simplest path. After payoff, use our Savings Goal Calculator to build an emergency fund so you do not rely on credit for surprises. See How to Pay Off Credit Card Debt Fast for a month-by-month plan.
FAQ
Should I pay off credit cards or save first?
Build a small emergency fund of $1,000 to $2,000 first, then focus on high-interest credit card debt. Cards near the 22.36% assessed-interest average cost far more than typical savings yields. Once high-interest debt is gone, redirect those payments toward a full emergency fund.
Does paying the minimum hurt my credit score?
Paying the minimum keeps your account in good standing and avoids late payment marks, but high credit utilization (balance relative to credit limit) can lower your score. Paying down balances reduces utilization and improves your score over time, even if you keep the accounts open.
What if I can only afford the minimum right now?
Pay the minimum on every card to avoid fees and penalties, then look for ways to increase income or reduce expenses — even temporarily. Every extra dollar above the minimum accelerates your payoff and reduces total interest.
Is it better to pay off one card or spread payments across all cards?
Always pay at least the minimum on every card to avoid penalties. Beyond that, concentrate extra payments on one card using either the avalanche method (highest APR first) or snowball method (smallest balance first). Spreading small extra amounts across multiple cards slows progress on all of them.