💰 Loan Calculator
Calculate interest for equal payment, equal principal, and bullet repayment plans
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30y 0m
[Equal Payment] Result
Monthly Payment
506,685 KRW
Total Interest
82,406,715 KRW
Total Payment
182,406,600 KRW
Repayment Plan Guide
Equal Payment: Pay the same amount every month. Predictable monthly payment.
Equal Principal: Pay the same principal every month. Relatively lower total interest.
Bullet: Pay only interest during the term, then repay the full principal at maturity.
Loan Interest Formulas
Equal Payment (Amortized)
Monthly payment = principal × monthly rate × (1+monthly rate)^months ÷ {(1+monthly rate)^months − 1}. Monthly rate is the annual rate divided by 12. You pay the same amount every month, but the interest portion is larger early on and the principal portion grows over time.
Equal Principal
The principal paid each month = loan principal ÷ number of months, and stays constant. Interest is calculated as the remaining balance × monthly rate, so as the balance shrinks, the monthly payment decreases over time.
Bullet (Interest-Only)
You pay only interest (principal × monthly rate) each month, then repay the full principal plus the final month's interest in one lump sum at maturity. Since the principal never decreases, total interest is the highest of the three plans.
Example (30,000,000 KRW principal · 5% annual rate · 36 months)
Equal Payment: about 899,127 KRW × 36 payments → total interest 2,368,570 KRW, total payment 32,368,572 KRW
Equal Principal: starts at 958,333 KRW and decreases each month → total interest 2,312,500 KRW, total payment 32,312,500 KRW
Bullet: 125,000 KRW interest-only each month, plus the full 30,000,000 KRW principal at the final month → total interest 4,500,000 KRW, total payment 34,500,000 KRW
Under identical terms, total interest can differ by up to about 2.13M KRW depending on the repayment plan. Equal principal has the lowest total interest but the highest initial burden; bullet repayment has the lowest initial burden but the highest total interest.
Frequently Asked Questions
Q. Which is better, equal payment or equal principal?
A. Equal principal results in lower total interest, but its early monthly payments are much higher than equal payment. If your income is steady, equal payment is easier to manage; if you can afford higher payments early on, equal principal saves more overall.
Q. How much interest do I save by repaying early?
A. Excluding any early repayment fee, you save interest on the remaining principal going forward. Repaying early in the loan term saves more. This calculator shows the standard schedule and does not account for early repayment.
Q. Should I choose a variable or fixed interest rate?
A. Variable rates move with the market, while fixed rates stay the same for the full term. A fixed rate can be advantageous if rates are expected to rise, and a variable rate if they're expected to fall.
Q. What happens to total interest if I extend the loan term?
A. A longer term lowers your monthly payment but increases total interest. In the example above, extending from 36 to 60 months lowers the monthly payment but raises the total interest paid.
Q. Why do the results differ from my actual bank loan?
A. Banks vary in origination fees, early repayment penalties, and preferential rate discounts, which can cause real repayment amounts to differ. Check with your lender for exact terms.