The schedule changes how a loan feels month to month
An amortization schedule shows how each payment is split between principal and interest. Paying principal lowers the balance; the next period’s interest is then calculated on a smaller amount. Two loans with the same balance, rate, and term can therefore have different payment patterns depending on when principal is repaid. Use the loan calculator to compare equal payments, equal principal, and a balloon structure under the same assumptions.
With an equal-payment schedule, the combined principal-and-interest payment stays nearly level. Early payments contain more interest because the outstanding balance is high. Later payments direct more of that same payment toward principal. With equal principal, each scheduled payment reduces principal by the same amount. Interest declines with the balance, so the total payment starts high and falls over time. With an interest-only or balloon schedule, regular payments cover interest while principal remains outstanding; the final payment includes the remaining principal.
Compare one example
Suppose you borrow $12,000 at 12% for 12 months. Choose monthly interest, no grace period, and cent rounding in the calculator.
| Method | First payment | Final payment | Total interest |
|---|---|---|---|
| Equal payment | $1,066.19 | $1,066.14 | $794.23 |
| Equal principal | $1,120.00 | $1,010.00 | $780.00 |
| Interest-only, balloon at maturity | $120.00 | $12,120.00 | $1,440.00 |
The equal-payment schedule has a small final-payment adjustment because cents cannot be divided perfectly across every installment. The equal-principal first payment combines $1,000 of principal with $120 of first-month interest. As the balance falls by $1,000 each month, monthly interest falls by $10. The balloon schedule keeps the original $12,000 balance through the term, so its interest payment stays at $120 each month and the last payment also returns the principal.
In this example, equal principal costs $14.23 less interest than equal payments, but its first payment is $53.81 higher. The balloon method has the smallest regular payment and the largest final payment, with the highest total interest of the three. Those results describe this example, not a universal ranking: the best fit depends on cash flow, contract terms, and the ability to meet the final payment.
Compare more than the regular payment
Enter the same principal, annual rate, and term before switching methods. Compare total interest and the balance remaining after each payment, not just the first monthly amount. The schedule can reveal whether the balance declines steadily or remains in place until maturity. You can expand the table or download it as a CSV to compare its rows with a lender’s payment schedule.
Check how the rate is applied. A monthly model divides the annual rate by 12. An actual-day model uses the number of days in each payment period and distinguishes ordinary years from leap years. The tool’s actual-day option can therefore produce different figures from the monthly example above. A real lender may also use contract-specific day-count conventions, payment dates, fees, prepayments, or rate changes. Use the same convention as the offer when comparing estimates.
A grace period changes the timing too. During the selected grace months, the calculator charges interest without reducing principal. The remaining principal is then repaid over the months left in the total term. Confirm whether a lender’s grace period is included in the stated term and whether unpaid interest is added to principal; those details affect later payments.
Read the contract before choosing
The calculator is a comparison aid, not a loan quote. A lender’s disclosure or contract controls the actual payment amounts. Review fees, rate changes, due dates, early-payment rules, and any balloon amount. Keep enough room in your budget for the first payment as well as the largest payment shown in the schedule. This article is general information, not financial advice.
For savings rather than borrowing, see simple versus compound interest. The Korean-language comparison is in 원리금균등·원금균등·만기일시 상환.
Read the schedule line by line
Each row lists a payment date, amount, principal, interest, and remaining balance. Review the first, a middle, and the final rows rather than judging the loan from the first payment alone. Equal payments keep the combined amount steady while the principal share grows. Equal principal reduces the balance faster at the beginning, which is why its interest falls more quickly. A balloon schedule needs special attention at maturity: a small regular payment does not mean the remaining balance has disappeared.
Change the term while keeping the amount and rate constant. A longer term often lowers the scheduled payment but leaves the balance outstanding for more periods, which can increase total interest. A shorter term can reduce the time interest accrues but may require a larger monthly budget. Compare both payment size and total interest, then consider whether your income can support the highest scheduled amount. The calculator does not model a future job loss, rate reset, early payment, or lender fee.
If you export the schedule, use it as a planning aid and keep the loan’s written disclosure beside it. The calculator’s rounding and date conventions may differ from the lender’s servicing system. If the numbers do not line up, compare the payment dates, day-count basis, rate, grace period, fees, and rounding rule one by one. Ask the lender to explain any remaining difference before signing. A spreadsheet cannot replace the payment terms in the signed note.