繰上返済シミュレーションツール
Enter your loan balance, interest rate, remaining term, monthly payment, and prepayment amount to estimate the interest saved, time shortened, and new payment for both the term-reduction and payment-reduction methods. Uses equal installment calculation and runs entirely in your browser.
Results are estimates based on a general equal-installment formula and do not constitute financial, lending, or investment advice or a recommendation of any specific product.
Actual payments, interest, prepayment fees, and terms vary by lender and contract. Always confirm exact figures with your financial institution.
The interest rate is assumed to be fixed for the simulation period. Variable rates may change the results.
All calculations run entirely in your browser; the amounts you enter are never sent to any server.
How to Use
Enter Loan Conditions
Enter your current loan balance, interest rate, and remaining term. Leave the monthly payment blank to auto-calculate it.
Set Prepayment Conditions
Enter the prepayment amount and how many years from now you plan to make it.
Check the Effect
Press "Simulate" to see the interest saved, term shortened, and new payment for both the term-reduction and payment-reduction methods.
About the Loan Prepayment Simulator
Prepayment means paying an extra lump sum on top of your regular payments to reduce the principal. This free tool estimates the interest you can save and the time you can shorten by prepaying, showing both the term-reduction and payment-reduction methods at once. It uses the equal-installment formula and is useful for planning repayment of mortgages, auto loans, and more.
Features
- Compare Two Methods at OnceSee term-reduction and payment-reduction effects side by side.
- Interest Savings at a GlanceShows exactly how much interest your prepayment removes.
- Privacy ProtectedAll calculations run in your browser. Amounts are never sent to a server.
- Free, No RegistrationNo install or sign-up. Works instantly on phone or PC.
Use Cases
- Deciding whether to put a bonus or savings toward a mortgage prepayment
- Comparing term-reduction vs payment-reduction methods
- Finding the best timing for a prepayment
- Understanding how much interest a prepayment removes
- Considering early payoff of an auto or education loan
FAQ
Which is better: term reduction or payment reduction?
What happens if I leave the monthly payment blank?
Is prepaying earlier more effective?
Will the results match my lender exactly?
Are the amounts I enter sent anywhere?
Feedback
Missing a feature, or getting a result that looks wrong? Let us know — we improve our tools based on your feedback.