Loan Interest Calculator

Equal payment (원리금균등): you pay the same total amount every month, with the interest-to-principal ratio shifting over time. Equal principal (원금균등): the principal is split evenly across all payments, so interest decreases each month — but your initial payments are higher.

With balloon repayment, you pay interest only each month and repay the entire principal as a lump sum at the end of the loan term.

The equal principal method results in less total interest. Because a fixed portion of the principal is repaid each month, the outstanding balance decreases more quickly, reducing the interest base. With equal payment, a larger share of early payments goes to interest, so the balance decreases more slowly and total interest is higher for the same loan terms. Note that equal principal has higher initial monthly payments, so consider your cash flow when choosing.

Making an early repayment reduces the outstanding principal on which future interest is calculated, resulting in interest savings. The earlier in the loan term you repay, the greater the savings. However, financial institutions may charge a prepayment penalty, so factor in that fee when estimating your actual net savings.

Extending the loan term slider reduces the monthly payment shown on the result card, but total interest actually increases significantly. For example, comparing a 10-year and a 30-year repayment with the same principal and rate, the monthly payment drops but total interest can more than double. Switch the term slider between 10, 20, and 30 years to directly compare how monthly payments and total interest respond.

Adjust the term slider to 10, 20, or 30 years and the monthly payment and total interest in the result cards update in real time. The repayment snapshot shows how the principal and interest portions shift across early, middle, and late installments, letting you intuitively compare the impact of term length under the same principal and rate.

The interest ratio on the result card is total interest divided by the loan principal — the lower this number, the more favorable the loan terms. Lowering the interest rate slider or shortening the loan term slider both reduce the interest ratio. Conversely, extending the term lowers the monthly payment but raises the interest ratio, creating a trade-off. Combine the rate and term sliders to explore how the interest ratio responds and find the optimal conditions for your situation.