Loan Interest Calculator

Calculate interest and monthly payments for mortgages, personal loans, and more. Compare equal principal & interest vs. equal principal repayment methods to find the best loan terms.

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How to Use

1. Enter Loan Amount

Enter the loan amount in KRW. For mortgages, up to 70% (LTV) of the property value is available. Personal loan limits depend on income and credit rating.

2. Enter Annual Interest Rate

Enter the annual interest rate as a percentage. Mortgage rates are typically 3.5~5.5%, and personal loan rates are 5~15%.

3. Select Loan Period

Select the repayment period in months. Mortgages typically range from 10~30 years (120~360 months), personal loans from 1~5 years (12~60 months).

4. Select Repayment Method

Equal Principal & Interest pays the same amount each month. Equal Principal divides the principal evenly, resulting in decreasing payments over time.

Real-World Examples

Example 1: First-time Home Purchase

A couple purchasing a 500M KRW apartment with 200M down payment, borrowing 300M at 4.5% for 30 years. Monthly payment: ~1.52M KRW, total interest: ~250M KRW.

Example 2: Business Operating Fund

A cafe owner borrowing 50M KRW at 7% for 3 years for renovation. Monthly payment: ~1.54M KRW, total interest: ~5.5M KRW.

Example 3: Jeonse Deposit Loan

Borrowing 300M KRW at 3.2% for 2 years for apartment deposit. Interest-only payments for first year (~800K/month), then principal repayment begins.

Tips to Reduce Loan Interest

  • Compare rates across multiple banks - even 0.5% lower saves millions
  • Check and improve your credit score before applying
  • Start repaying immediately without grace period to reduce total interest
  • Choose products without early repayment penalties
  • Exercise your annual rate reduction request right
  • Check if income deductions are available for your loan type
  • Set loan limits generously but only use what you need

FAQ

Which repayment method is better?

If your income is stable, Equal Principal saves 10~20% on total interest. For a 300M KRW loan at 4% over 20 years, the difference is about 7M KRW. However, if cash flow is tight initially, Equal Principal & Interest offers more predictable payments.

How are loan interest rates determined?

Rates = Base rate + Spread. Base rates follow the Bank of Korea rate or COFIX. Spread depends on credit rating (0~5% difference), income, collateral value, and loan term.

What are early repayment penalties?

Early repayment fees are typically 0.5~1.4% of the repaid amount, charged within the first 3 years. Low-income borrowers may be exempt since 2023.

What are LTV, DTI, and DSR?

LTV (Loan-to-Value): max loan vs. property value (typically 70%). DTI (Debt-to-Income): annual repayments vs. income (max 50%). DSR (Debt Service Ratio): stricter than DTI, includes all loans (max 40%).

How long does loan approval take?

Personal loans: 1~3 days. Mortgages: 1~2 weeks. Prepare income verification, ID, and other documents in advance for faster processing.

When should I refinance?

Refinance when rates drop 1%+ below your current rate. Consider early repayment fees (0.5~1.4%) and new loan fees (~500K KRW). A 1% reduction on 200M KRW over 10 years saves ~10M KRW.

What is the difference between interest-only and standard loans?

Interest-only loans defer principal payments for 1~3 years, reducing initial burden but increasing total interest by 20~30%. Plan carefully as payments increase significantly after the grace period.

Disclaimer

This calculator is for reference only. Actual loan terms vary by bank, credit rating, income, and collateral. Please consult a financial institution for accurate rates and conditions. Excessive borrowing may affect your credit score.

대출 이자 계산의 원리와 구조

대출 이자는 금융기관이 자금을 빌려주는 대가로 받는 비용으로, 대출 원금에 이자율을 적용하여 계산됩니다. 대출 이자의 기본 공식은 '이자 = 원금 × 이자율 × 기간'이지만, 실제 대출에서는 매월 원금 잔액이 변동하기 때문에 더 복잡한 계산이 필요합니다. 이자율은 연이율(年利率)로 표시되며, 월별 계산 시에는 연이율을 12로 나눈 월이율을 사용합니다. 예를 들어 연 4.8% 금리는 월 0.4%에 해당합니다.

원리금균등상환 vs 원금균등상환: 핵심 비교

원리금균등상환은 매월 동일한 금액을 납부하는 방식으로, 초기에는 이자 비중이 높고 후반부로 갈수록 원금 비중이 높아집니다. 월 납부액이 일정해 자금 계획이 쉬운 반면, 총 이자 부담이 원금균등상환보다 다소 많습니다. 원금균등상환은 매월 동일한 원금을 상환하고 남은 원금에 대한 이자를 추가로 납부하는 방식으로, 초기 납부액이 가장 높고 점차 줄어듭니다. 총 이자 부담이 적지만 초기 상환 능력이 충분해야 유리합니다. 소득이 안정적이고 초기 여유 자금이 있다면 원금균등상환이, 매월 일정한 지출 관리를 원한다면 원리금균등상환이 적합합니다.

대출 비교 및 절감을 위한 실전 팁

대출 이자를 절감하는 가장 효과적인 방법은 여러 금융기관의 금리를 비교하는 것입니다. 주택담보대출의 경우 은행마다 0.3~1%의 금리 차이가 있을 수 있으며, 3억 원 대출 기준으로 금리 0.5% 차이는 30년간 약 2,500만 원의 이자 차이를 만듭니다. 또한 신용등급 관리를 통한 가산금리 인하, 대출 실행 전 금리인하요구권 행사, 중도상환 수수료가 없는 상품 선택, 그리고 변동금리와 고정금리의 시장 상황에 맞는 선택도 중요한 절감 전략입니다. 온라인 대출 비교 플랫폼을 활용하면 다양한 상품을 한눈에 비교할 수 있습니다.

This calculator is provided for informational purposes only.

Results are estimates and may differ from actual amounts.

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