Loan repayment calculator
Monthly payment, total interest and a full schedule for three repayment methods.
Input
What actually lands in the account, before fees.
The nominal rate. A variable-rate loan is computed at the current rate.
Years and months are added together.
Months that pay interest without touching the principal, which raises the total interest.
Result
The same amount every month. Interest is charged on the balance, so the principal share grows over time — and the longer the term, the more of the early payments is interest. The default for mortgages.
Monthly payment
₩1,050,906
- Total interest
- ₩26,108,748
- Total repaid
- ₩126,108,748
- Interest as a share of the loan
- 26.1%total interest ÷ amount borrowed
The three methods compared
Same amount, rate and term. The method with the smallest monthly payment always costs the most interest.
| Method | Monthly | Total interest |
|---|---|---|
| Equal payment | ₩1,050,906 | ₩26,108,748 |
| Equal principal | ₩1,233,333 → ₩836,667 | ₩24,200,000 |
| Interest only | ₩400,000 → ₩100,400,000 | ₩48,000,000 |
Repayment schedule
| Period | Payment | Interest | Principal | Balance |
|---|---|---|---|---|
| Year 1 | ₩12,610,875 | ₩4,625,849 | ₩7,985,026 | ₩92,014,974 |
| Year 2 | ₩12,610,875 | ₩4,234,022 | ₩8,376,853 | ₩83,638,121 |
| Year 3 | ₩12,610,875 | ₩3,822,968 | ₩8,787,907 | ₩74,850,214 |
| Year 4 | ₩12,610,875 | ₩3,391,744 | ₩9,219,131 | ₩65,631,083 |
| Year 5 | ₩12,610,875 | ₩2,939,359 | ₩9,671,516 | ₩55,959,567 |
| Year 6 | ₩12,610,875 | ₩2,464,776 | ₩10,146,099 | ₩45,813,468 |
| Year 7 | ₩12,610,875 | ₩1,966,904 | ₩10,643,970 | ₩35,169,498 |
| Year 8 | ₩12,610,875 | ₩1,444,603 | ₩11,166,272 | ₩24,003,225 |
| Year 9 | ₩12,610,875 | ₩896,671 | ₩11,714,204 | ₩12,289,022 |
| Year 10 | ₩12,610,875 | ₩321,853 | ₩12,289,022 | ₩0 |
A lender's own figures will differ slightly: day-count conventions, the payment date and rounding all shift the result. Early-repayment charges, stamp duty, guarantee fees and registration costs are not included. Check the schedule your lender provides before signing.
Saving rather than borrowing? Use the deposit and savings calculator.
How to use
- Enter the amount borrowed and the annual rate.
- Enter the term in years and months; the two are added together.
- Pick a repayment method — all three are compared below regardless.
- Add an interest-only period if the loan has one.
- Read the schedule to see how the interest and principal shares move.
Frequently asked questions
Which method costs less?
Equal principal, always. It cuts the balance fastest, so less interest accrues. The trade-off is that the first payment is the largest, which needs early cash flow. Equal payment is easier to budget because the amount never changes.
Why does a smaller monthly payment cost more overall?
Interest is charged on what is still owed. A smaller payment leaves the balance high for longer, so interest accrues on a bigger number for more months. Interest-only repayment never reduces the balance at all, so it costs the most.
What does an interest-only period cost?
The interest for those months is added on top, and the principal then has to be repaid over a shorter remaining term, which raises the monthly payment too. Change the interest-only months here to see the effect on a specific loan.
Are early payments really almost all interest?
Only on long terms. At 4.8% over 30 years, 76% of the first payment is interest; over 10 years at the same rate it is 38%. Shorter terms repay principal from the start.
Why does my lender's figure differ?
Lenders accrue interest on a daily basis, round to whole units, and account for the gap between drawdown and the first payment date. This is the standard monthly calculation, so expect small differences per payment.
About the Loan calculator
The same amount borrowed costs materially different totals depending on how it is repaid. A conversation with a lender tends to centre on the monthly payment, and this page puts the total interest next to it so the trade-off is explicit.
The schedule is the substance here. Seeing which payment first repays more principal than interest, and when the balance passes halfway, gives a basis for choosing a term or timing an overpayment. Every total is summed from that schedule, so the table and the headline figures always agree.
These are standard monthly calculations without fees, so treat them as a planning tool and check the lender's own schedule before signing.