The Credit Card Calculator estimates how long a card balance takes to clear and how much interest accrues at a chosen payment. Enter the balance, APR, and monthly payment (or a minimum-payment rule), and the Credit Card Calculator returns months to payoff, total interest, and a period-by-period view of how the balance falls.
Revolving credit looks simple on a statement and expensive in practice when only the minimum goes out each month. The Credit Card Calculator makes that path concrete with the same amortization-style maths used for installment loans, adapted to card APR and billing conventions.
*These results are estimates for information only, not financial or investment advice. Issuer fees, penalty APRs, and grace periods can change real costs.*
Calculate credit card payoff and interest
The Credit Card Calculator calculates credit card payoff and interest by amortizing the balance at the monthly rate implied by the APR while applying each payment first to interest and then to principal. Payoff time is the number of billing cycles until the balance reaches zero at that payment level.
Monthly rate is APR divided by 12 for a standard model (for example 18% APR gives 1.5% per month). On a $5,000 balance at 18% APR with a fixed $150 payment, months to payoff equal ln(PMT / (PMT - PV x r)) / ln(1 + r), about ln(150 / 75) / ln(1.015), about 46.6 months, so about 47 statements. Total of the payments is roughly $6,975 to $7,000 depending on the final stub payment, which means roughly $1,975 to $2,000 in interest on top of the $5,000 principal. The Credit Card Calculator shows interest total beside the schedule so the cost of carrying the balance is visible.
Raising the fixed payment shortens the term sharply because more of each cycle hits principal once interest is covered. Dropping the payment toward the interest-only line stretches the term without bound.
Escape the minimum payment trap
The Credit Card Calculator illustrates the minimum payment trap: when the required payment is a small percent of the current balance (often around 1% to 3% plus interest, or a flat floor such as $25 to $35), the payment shrinks as the balance falls and payoff stretches for years.
Suppose a $5,000 balance at 22% APR and a minimum equal to the greater of $25 or 2% of the balance. Early payments are about $100, but they decline as principal declines, so the card stays open far longer than a fixed $150 plan. Interest in the early years can rival or exceed principal reduction. The Credit Card Calculator compares that shrinking minimum path to a fixed higher payment on the same balance and APR, which is the practical escape: pick a dollar amount that does not fall with the balance.
Issuers publish their own minimum formulas. Treat the tool's minimum mode as an educational model matching the rule you enter, not a clone of every cardholder agreement. Penalty APR after a late payment can widen the trap further; the model assumes the APR entered stays fixed.
Understand the daily periodic rate
The Credit Card Calculator uses the daily periodic rate to explain how APR becomes daily interest on many United States-style cards. Daily periodic rate equals APR divided by 365, though some issuers use 360. Statement methods then apply that rate to average daily balance.
At 22% APR, the daily periodic rate is 0.22 / 365, about 0.0006027, or about 0.06027% per day. Average daily balance methods multiply that rate by each day's balance and sum across the billing cycle. The Credit Card Calculator's simpler monthly model (APR/12) is a close planning approximation; statement interest may differ slightly when the issuer posts daily accrual and includes new purchases. Grace periods can waive interest on new purchases if the previous balance was paid in full; carrying a revolving balance usually ends that grace on new spend.
Reading the APR and the daily rate together shows why a high rate hurts even when the dollar balance looks moderate. A $1,000 average daily balance at that 22% APR accrues roughly $0.60 of interest per day before fees.
See the payoff schedule
The Credit Card Calculator shows a payoff schedule with each month's payment, interest portion, principal portion, and remaining balance. The schedule is the proof behind the headline months and interest totals. Assumptions of fixed APR and no new charges stay on the page.
For the $5,000, 18% APR, $150 payment case, month 1 interest is about $5,000 x 0.015 = $75, so principal reduction is $75 and the new balance is $4,925. Month 2 interest is $4,925 x 0.015, about $73.88, and so on, until the final month's payment is truncated to the remaining balance plus that month's interest. The Credit Card Calculator lists those rows so a reader can verify the path rather than trusting a single payoff date. Comparing two schedules (minimum versus fixed) is often clearer than comparing two summary numbers alone.
Assumptions stay on the page: fixed APR, no new charges, no fees, payment posted each cycle. New purchases reset the story. For months-to-payoff and target-date payment as the primary question, use the Credit Card Payoff Calculator on the same maths with a tighter focus.
Frequently asked questions
How does the Credit Card Calculator estimate payoff time?
The Credit Card Calculator estimates payoff time by applying each payment to interest and principal until the balance reaches zero. At $5,000, 18% APR, and $150 per month, payoff takes about 47 months. Total interest is on the order of $2,000 under those inputs.
What is the minimum payment trap?
The minimum payment trap is the long payoff that occurs when the required payment shrinks with the balance. The Credit Card Calculator models a percent-of-balance minimum and contrasts it with a fixed payment. Paying only the minimum can keep a balance open for many years and multiply interest.
What is the daily periodic rate?
The daily periodic rate is APR divided by 365 (or 360 on some cards). The Credit Card Calculator references that rate to explain statement interest. At 22% APR, the daily rate is about 0.06027% per day.
Does the calculator include new purchases?
The calculator does not include new purchases unless they are added to the starting balance. The Credit Card Calculator assumes a fixed balance being paid down. New spend lengthens payoff and can remove purchase grace periods.
How can payoff interest be reduced?
Payoff interest can be reduced by raising the fixed monthly payment, lowering the APR (for example with a transfer offer), or both. The Credit Card Calculator recalculates months and interest when those inputs change. Extra principal each month cuts the balance that future interest can charge.
Is APR the same as effective annual rate?
APR on a card is the stated annual rate used for periodic interest; effective annual rate can be higher once compounding is considered. The Credit Card Calculator focuses on statement-style payoff. Use the Effective Annual Rate Calculator when comparing compounding conventions across products.
Summary
The Credit Card Calculator amortizes a revolving balance at the APR-derived monthly rate to show months to clear, total interest, and a payment schedule. A $5,000 balance at 18% APR with a fixed $150 payment takes about 47 months and roughly $2,000 in interest, while a shrinking minimum payment can stretch far longer on the same APR.
Daily periodic rate (APR/365) explains how issuers accrue interest inside a cycle. Results assume no new charges and a stable APR. These results are estimates for information only, not financial advice.