Korea Loan Interest Calculator
Last updated: 2026-06-25
This loan interest calculator takes the loan principal, annual rate and term and computes the monthly payment and total interest for equal payment, equal principal and bullet repayment methods.
Equal-payment monthly amount = principal × monthly rate × (1+monthly rate)^months ÷ ((1+monthly rate)^months − 1), where monthly rate = annual rate ÷ 12.
Enter loan details
Monthly payment
0 KRW
How to use
- Enter loan details — Enter the loan principal, annual rate (%) and term (months).
- Choose repayment method — Choose one of equal payment, equal principal or bullet.
- View the result — Press Calculate to see the monthly payment, total interest and total repayment.
Three loan repayment methods compared
Loan repayment methods fall into three types: equal payment, equal principal and bullet. With the same principal, rate and term, the monthly payment and total interest change significantly depending on the method.
| Method | Monthly payment | Total interest | Notes |
|---|---|---|---|
| Equal payment | Same each month | Medium | Easy to plan, most common |
| Equal principal | High early, then falls | Lowest | Balance falls fast, saves interest |
| Bullet | Interest only (lowest) | Highest | Repay principal at maturity |
Formulas
- Equal payment: Monthly payment = P × r × (1+r)n ÷ ((1+r)n − 1), where P=principal, r=monthly rate (annual rate÷12), n=months.
- Equal principal: Monthly principal = P ÷ n, monthly interest = balance × r (interest falls as the balance shrinks).
- Bullet: Monthly interest = P × r, full principal P repaid at maturity.
To learn which method is best for you, see our guide Equal payment vs equal principal vs bullet: which is best?
Frequently asked questions (FAQ)
What is the difference between equal payment and equal principal?
With equal payment the total amount paid each month (principal + interest) is the same, which makes budgeting easy. With equal principal the principal portion is the same each month, so early payments are larger but the balance falls faster and total interest is lower. For the same terms, equal principal has less total interest than equal payment.
How does bullet repayment work?
With bullet repayment you pay only interest each month and repay the entire principal at maturity. The monthly burden is the lowest, but because the principal never falls, total interest is the highest. It is common for jeonse deposit loans and short-term credit loans.
How is the equal-payment monthly amount calculated?
Monthly payment = principal x monthly rate x (1 + monthly rate)^months / ((1 + monthly rate)^months - 1). The monthly rate is the annual rate divided by 12.
Which method minimizes total interest?
By total interest alone, equal principal is the lowest, then equal payment, then bullet. However, equal principal has the highest early monthly payment, so weigh it against your current income and ability to repay.
Does it include early repayment fees?
This calculator only computes the interest and payments when repaying as scheduled and does not include early repayment fees. Early repayment fees vary by institution, product and elapsed time, so check your loan agreement.
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Last updated: 2026-06-25