Estimate a fixed-payment debt schedule
Enter one balance, a fixed annual loan interest rate and a monthly payment. The calculator estimates repayment time and interest under a monthly model. A separate goal in whole months calculates the smallest cent-denominated payment that clears this model by that deadline. A longer goal can increase total interest, so it is not always an accelerated plan.
How the calculation works
The monthly rate is the nominal annual interest rate divided by 12, expressed as a decimal. Interest is rounded to the nearest cent each month. Payment first covers that interest; the remainder reduces principal. The final payment is reduced to the amount still owed. Input balances and payments are rounded to cents.
The starting annuity formula is M = P × r ÷ (1 − (1 + r)−n). At zero interest, M = P ÷ n. The calculator then finds the smallest cent payment that meets the goal under its rounded-interest schedule. Results beyond 1,200 months, non-amortizing payments, invalid values and numerical overflow are rejected rather than shown as paid off.
Enter the contract interest rate. A loan APR may include fees and is not interchangeable with the interest rate used to accrue this schedule. See the CFPB explanation of loan interest rates and APR.
Worked example: $25,000 at 6.5%
With a $500 monthly payment, first-month interest is $135.42 and principal repayment is $364.58. Under this calculator’s cent-rounded monthly model, payoff takes 59 months and total interest is $4,234.87. A 36-month goal requires $766.23 per month, with a smaller final payment and total interest of $2,584.10. That reduces modeled interest by $1,650.77. These are calculations from stated inputs, not observed borrower results.
$500/month
59 months · $4,234.87 interest
$766.23/month
36 months · $2,584.10 interest
Compare the estimate with your loan terms
- Check the balance, contract interest rate and required payment on your statement.
- Enter a monthly payment and a whole-month goal from 1 to 1,200. Click Calculate; subsequent edits update the results.
- Review the smaller final payment and both schedules. A blank or invalid goal does not invalidate a valid current-payment schedule.
- Ask the lender how additional payments are applied, whether prepayment charges apply, and whether interest accrues daily. Obtain the lender’s payoff quote before settling a loan.
Prioritizing several debts
This calculator models one debt at a time. For multiple debts, the highest-interest method directs extra funds to the costliest rate while maintaining required payments elsewhere. The snowball method directs extra funds to the smallest balance; it may make progress easier to see but can cost more interest. The CFPB describes both methods and their tradeoffs.
Balance transfers and consolidation are separate financing decisions. Compare transfer or origination fees, promotional expiry, subsequent rates and repayment terms. A lower monthly payment from a longer term can increase total cost. Those fees and changing rates are not included here.
Model limits
The schedule assumes month-end payments, no new borrowing, no missed payments, no fees and no rate changes. Daily-accrual loans, changing credit-card minimums, multiple APR balances, promotional rates and precomputed interest can produce different outcomes. The calculator does not process payments or provide an official lender payoff quote.