Repayment Calculator
Work out how to repay any balance — credit card, personal loan, auto loan, or mortgage. Solve for the payment that clears it in a fixed time, or for how long a fixed payment takes, with full control over compounding and payment frequency.
Principal vs. interest
💸 Refinancing could shrink this payment — compare rates
Check your rateHow repayment works
Every payment first covers the interest that accrued since the last one; whatever remains reduces principal. Early in a loan the interest slice is biggest, and it shrinks as the balance falls — which is why the last year of a loan feels like fast-forward. The two solve modes are mirror images: fix the time and the formula sets your payment; fix the payment and the formula sets your time. If a payment only just covers interest, payoff time heads toward infinity — the minimum-payment trap on credit cards.
How it’s calculated
The quoted rate is converted to an exact per-payment rate: i = (1 + r÷m)m/k − 1 for compounding m times a year with k payments a year (i = er/k − 1 for continuous). Fixed term: payment = P × i ÷ (1 − (1 + i)−n) with n = years × k. Fixed payment: n = −ln(1 − P×i÷W) ÷ ln(1 + i). Totals come from a payment-by-payment simulation, so the final partial payment is exact.
Assumes a fixed rate and on-time payments with no fees or prepayment penalties. Estimates only — verify terms with your lender.
Repayment schedule by year
Interest and principal totals per year at your chosen payment frequency.
Worked example
A $15,000 balance at 8% (compounded monthly) repaid monthly over 4 years needs $366.19 a month — $17,577 in total, of which $2,577 is interest. Flip to fixed-payment mode at $400 a month and payoff takes 3 years 8 months (44 payments, the last one partial), costing $2,319 in interest — $258 saved. Prefer weekly payments over the same 4 years? That is $84.29 a week.
Common mistakes
- Treating an 8% APY quote as if it were an 8% APR — the compounding basis changes the per-month cost.
- Choosing a payment barely above the interest charge and wondering why the balance barely moves.
- Comparing loans by payment size when the payment frequencies differ — compare total interest instead.
- Ignoring prepayment penalties before switching to an aggressive payoff plan.
Where it is used
- Turning “I can spare $400 a month” into an actual debt-free date.
- Checking what a 15- versus 30-year horizon does to a payment and to total interest.
- Modeling biweekly or weekly payment plans lenders offer.
- Planning payoff of a card balance at a fixed self-imposed payment.
Frequently asked questions
What's the difference between the two solve modes?
Fixed term answers: what payment retires the balance in exactly this long? Fixed payment answers: at the amount I can afford, when am I done? Same formula, solved for a different unknown — $15,000 at 8% needs $366.19 a month for 4 years, while $400 a month finishes in 3 years 8 months.
Why does paying $34 more a month finish 4 months early?
Every dollar above the interest charge reduces principal, and future interest is charged on the smaller balance. Raising the payment from $366.19 to $400 also cuts total interest from $2,577 to $2,319 — the effect compounds in your favor.
What does the compounding option change?
It defines what the quoted rate means. Monthly (APR) is standard for U.S. consumer loans; annually (APY) means the rate is the true yearly cost; daily or continuous compounds harder for the same nominal number. The calculator converts your quoted rate to an exact per-payment rate, so an 8% APY costs slightly less per month than an 8% APR.
What if my payment doesn't cover the interest?
The balance grows instead of shrinking — negative amortization — and the loan never pays off. On $15,000 at 8% compounded monthly, interest runs $100 a month, so any fixed payment at or below that gets flagged as never repaying.
Can I use this for credit cards?
Yes, in fixed-payment mode: enter the balance and APR and the payment you plan to make every month. That mirrors how revolving debt actually gets repaid — the card’s own minimum payment shrinks with the balance and stretches payoff much longer.