Estimated payoff time and supporting figures
Interest accrues once per month before a fixed payment. The final payment is capped at the balance plus that month’s interest. Payments that do not reduce the balance are rejected.
To compare a scheduled installment loan with optional extra principal payments, use the Loan Calculator with its amortization-term inputs.
The formula
Interest accrues once per month before a fixed payment. The final payment is capped at the balance plus that month’s interest. Payments that do not reduce the balance are rejected.
Worked credit card payoff example
A 3,000 balance at 20% APR repaid with 150 monthly takes 25 payments in this model. At zero APR, the same balance takes 20 payments and costs no interest.
How to use this calculator
- Enter current card balance, annual percentage rate.
- Set fixed monthly payment using the stated units or choices.
- Calculate and compare estimated payoff time, total modeled interest, total payments, final payment.
Choosing inputs for credit card payoff
Enter a fixed amount you can pay each month rather than a percentage-based minimum payment. Issuers can change their required minimum as the balance decreases; that behavior is outside this plan. A fixed payment helps show how maintaining an amount above a shrinking minimum changes the payoff path.
The annual rate is converted to a monthly rate for a transparent planning estimate. A credit-card statement may instead apply daily balances, separate APRs for transaction types, a grace period, and daily compounding. Those details can make actual charges differ even when the quoted APR matches the input.
Interpreting estimated payoff time
Do not add new purchases if you want the modeled payoff date to remain meaningful. Every payment first covers the month’s interest, and the remainder reduces principal. A payment equal to or below opening-month interest cannot start paying down the balance in this model, so it returns a useful input error instead of an infinite number of months.
Assumptions & limitations
What this calculation assumes
- No new transactions or fees are added, and APR remains fixed.
- Payments arrive at the end of each modeled month.
What to keep in mind
- Grace periods, issuer minimums, promotional rates, balance categories, and daily interest conventions are excluded. Plans exceeding 3,600 months are rejected.
Common questions
Why does a low payment return an error?
If the payment does not exceed monthly interest, the balance cannot decline under the model.
Does this calculate a required minimum?
No. It models the fixed payment you choose; consult the card agreement for minimum-payment rules.
Why is the final payment smaller?
The last installment is limited to the remaining balance plus that month’s modeled interest, avoiding an overpayment.
Sources & further reading
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