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Loan Repayment Calculator

Builds a repayment schedule for equal-payment, equal-principal or interest-only loans, with early repayment.

The same principal, rate and term produce quite different schedules depending on whether the payment or the principal is held constant, and the total interest differs by a noticeable amount. This builds the schedule month by month for either, and for interest-only, with early repayment.

🔒 Runs entirely in your browserloaninterestfinancecalculator

The loan

Months of interest only. It is not free — the same principal is carried for longer.

Repayment type

The same amount every month. The default for a mortgage, and the one with the most total interest.

Early repayment

Usually charged only within the first three years, tapering as they pass.

For the DSR

Summary

First payment

1,467,052원

Total interest

228,138,548원

Total paid

528,138,720원

Payments

360

monthly payment = principal × monthly rate ÷ (1 − (1 + monthly rate)^−months)
                = 300,000,000 × 0.3500% ÷ (1 − (1 + 0.3500%)^−360)
                = 1,467,052원

DSR — debt service ratio

DSR for this loan alone

29.3%

Bank limit

within (40%)

Non-bank limit

within (50%)

The assessment adds the repayments on every other loan, so the real figure will be higher than this. How much you can borrow is decided here far more than by the interest rate.

Repayment schedule

#PaymentintegerAmountintegerInterestintegerPrincipalintegerBalanceinteger
1114670521050000417052299582948
2214670521048540418511299164437
3314670521047076419976298744461
4414670521045606421446298323015
5514670521044131422921297900094
6614670521042650424401297475693
7714670521041165425887297049807
8814670521039674427377296622429
9914670521038179428873296193556
101014670521036677430374295763182
111114670521035171431880295331302
121214670521033660433392294897910
131314670521032143434909294463001
141414670521030621436431294026570
151514670521029093437959293588612
161614670521027560439491293149120
171714670521026022441030292708091
181814670521024478442573292265517
191914670521022929444122291821395
202014670521021375445677291375719
212114670521019815447237290928482
222214670521018250448802290479680
232314670521016679450373290029308
242414670521015103451949289577359
252514670521013521453531289123828
262614670521011933455118288668710
272714670521010340456711288211999
282814670521008742458310287753689
292914670521007138459914287293776
Interest is the annual rate ÷ 12 applied to the balance each month. That is the conversion Korean banks use in their published schedules; the compounded form ((1+r)^(1/12)−1) gives a payment about a per cent lower and disagrees with the statement you will receive. Margins, preferential rates and variable-rate adjustments are not modelled.

How to use it

  1. Enter principal, rate and term

    The rate is the nominal annual figure the loan is quoted at; interest is computed monthly from it.

  2. Compare the two repayment types

    원리금균등 keeps the monthly payment flat and back-loads the principal; 원금균등 pays more early and less later and costs less in total interest. Which is better is a cash-flow question, not an arithmetic one.

  3. Model the early repayment

    Paying down principal saves the interest that would have accrued on it for the rest of the term, which is why an early repayment early in the term is worth several times the same amount late in it.

Common questions

Does this include the early repayment fee?

The fee is an input, because it varies by product — a percentage that tapers over the first three years is common but not universal. Enter yours from the loan agreement.

Why does my bank’s figure differ by a little?

Day-count conventions and rounding. A lender may compute interest on actual days rather than on a twelfth of a year, and rounds each instalment to the won its own way. The difference is small and structural, not an error in either.

Can it handle a variable rate?

Not as a forecast — nobody can schedule a rate that has not been set. Run the schedule at a few rates to see the range, which is the honest form of that question.

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These accept what this tool produces, so the result can go straight in.

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