Loan Repayment Simulator
The Loan Repayment Simulator instantly calculates monthly payments, total repayment, and total interest for mortgages, auto loans, and education loans. Supports both equal installment and equal principal methods with automatic repayment schedule generation. Browser-based with no data transmission.
What You Can Do
The Loan Repayment Simulator is a browser-based tool for calculating loan repayments instantly for mortgages, auto loans, and education loans. Supports both equal installment and equal principal payment methods, allowing you to compare total payments with different interest rates and repayment periods. Perfect for repayment planning and preparation before consulting financial institutions. All calculations are performed in your browser, and no data is sent to servers.
- ✅ Monthly Payments: Calculate instantly based on your input
- ✅ Total Payment & Interest: Understand your complete repayment plan
- ✅ Repayment Schedule: Automatically generate monthly payment breakdown
- ✅ Payment Method Comparison: Compare equal installment vs equal principal
Calculate loan repayments instantly for mortgages, auto loans, and education loans. Supports both equal installment and equal principal payment methods. Free browser-based tool for repayment planning.
Notice
This simulation result is for reference only. Actual repayment amounts may vary depending on financial institutions. Please confirm with your financial institution.
Loan Simulation
Fixed monthly payments. Easy to plan your budget.
Enter between 1.1 and 100,000 (×10,000 yen)
Enter 200% or less
Enter between 1 and 360 months
Enter loan details in the form
and click "Calculate"
💼 Use Cases
- Mortgage Planning - Simulate monthly payments to determine your budget
- Auto Loan Comparison - Compare total payments with different rates and periods
- Education Loan Planning - Simulate affordable repayment plans in advance
- Home Improvement Loan - Calculate monthly payments from loan amount and period
- Payment Method Comparison - Compare equal installment vs equal principal
How to Use
📌 Basic Usage
Select a payment method, enter loan amount, annual rate, and repayment periods, then click "Calculate".
💡 Payment Method Differences
Feature: Fixed monthly payments
Benefits: Easy budget planning, lower initial burden
Drawbacks: Higher total interest than equal principal
Feature: Fixed monthly principal (total payment gradually decreases)
Benefits: Lower total interest, faster principal reduction
Drawbacks: Higher initial payments
📊 Input & Notes
Enter loan amount in units of 10,000 yen, annual rate in %, and repayment periods in months. This simulation is an estimate. Actual repayment amounts may vary due to fees and guarantees. Always confirm with your financial institution.
📚 Essential Loan Knowledge
🔄 Equal Installment vs Equal Principal: Differences & Selection Criteria
Loan repayment methods are broadly divided into two types, each with distinct characteristics. Understanding these differences is crucial when selecting a payment method.
| Item | Equal Installment | Equal Principal |
|---|---|---|
| Monthly Payment | Always constant | Highest initially, gradually decreases |
| Calculation Method | Complex formula for fixed monthly amount | Simple (Principal ÷ Periods + Interest) |
| First Payment | Moderate interest portion | Maximum interest portion |
| Final Payment | Minimum interest portion | Almost zero interest |
| Total Interest | Higher | Lower |
| Balance Reduction Rate | Slow initially, accelerates later | Steady from the start |
| Best For | Those wanting lower initial burden | Those wanting to minimize total payment |
💡 Selection Tip: Choose Equal Installment to reduce initial household burden, or Equal Principal to reduce total payment. However, about 95% of Japanese bank mortgages use equal installment, so actual options may be limited.
📐 Repayment Formulas and Interest Mechanism
Total loan repayment consists of the principal and interest. Understanding how interest is calculated enables better loan decisions.
Equal Installment Formula
Monthly Payment = Principal × Monthly Rate × (1 + Monthly Rate)Periods ÷ ((1 + Monthly Rate)Periods - 1)
Monthly Rate = Annual Rate ÷ 100 ÷ 12
Equal Principal Formula
Monthly Principal Payment = Principal ÷ Periods
Interest for Period n = Balance × Monthly Rate = (Principal - Monthly Principal Payment × (n - 1)) × Monthly Rate
Interest Concept
- Interest is the "usage fee" for borrowed money. The larger the remaining balance, the larger the interest amount
- For 1.5% annual rate on 30 million yen: First month interest is "30 million yen × 1.5% ÷ 12 = 375,000 yen"
- Total interest varies greatly with repayment period and interest rate. For the same 30 million yen, 0.5% vs 2.0% rates differ by millions of yen
💡 Example: For 30 million yen at 1.5% annual rate for 30 years (360 months), equal installment monthly payment is about 123,000 yen, total payment about 44.3 million yen, total interest about 14.3 million yen.
⏱️ Benefits and Effective Use of Early Repayment
Early repayment (prepayment) means paying off the remaining balance ahead of schedule, in addition to regular payments. Understanding this mechanism can significantly reduce total repayment.
Benefits of Early Repayment
- Reduced Total Interest: The shorter the repayment period, the dramatically lower the interest paid. Shortening a 30-year loan to 25 years can save millions of yen
- Psychological Relief: Seeing the loan balance visibly decrease provides mental peace of mind
- Rate Increase Risk Mitigation: Whether fixed or variable rate, lower balance means less impact from rate increases
- Life Stage Adaptation: Reducing loan balance before periods of increased expenses (e.g., children's education) makes household management easier
Early Repayment Examples
【Conditions】
Principal: 30 million yen / Annual Rate: 1.5% / Period: 30 years (360 months)
【Regular Payment Only】
Monthly Payment: ~123,000 yen / Total Payment: ~44.3 million yen / Total Interest: ~14.3 million yen
【1 Million Yen Prepayment at Year 10】
Remaining period shortened, future interest reduced. Total interest savings: ~1.5-2 million yen
【Additional 20,000 Yen Monthly】
Period shortened by ~4 years, total interest savings: Over 4 million yen
Types and Precautions
- Period Reduction Type: Keep same monthly payment, shorten period. Large effect, but monthly burden unchanged
- Payment Reduction Type: Keep same period, reduce monthly payment. Lighter household burden, but smaller interest reduction than period reduction
- Check Fees: Some financial institutions charge fees for early repayment. Confirm that interest savings outweigh fees
- Check Insurance Coverage: Mortgage loans include credit life insurance, so consider risk management for unexpected situations
💡 Best Practice: When you have surplus funds, prioritize repaying higher-rate loans first. The stable "return" from interest savings through early repayment cannot be matched by savings or investments.
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