Mortgage Extra Payment Calculator
See how a recurring extra principal payment can change payoff time and total interest. The calculator uses only the rate and remaining balance you enter; it does not present a live market rate.
Illustrative level-payment amortization in Japanese yen only. It excludes fees, prepayment penalties or minimums, variable-rate changes, insurance, taxes, rounding used by the lender, and differences between term-reduction and payment-reduction procedures. Confirm how extra payments are applied before sending money.
Enter your scenario
Use the details that match your situation. Your estimate stays in this browser.
How this estimate works
- The baseline monthly payment is calculated from the entered remaining balance, annual rate, and remaining months; a zero-interest loan uses simple principal division.
- A month-by-month schedule applies interest first, then the normal payment and entered extra principal without allowing the balance to fall below zero.
- The result compares estimated payoff months and total interest, but it is not an approval decision or lender quote.
Official sources
- Japan Housing Finance Agency: repayment-method change and partial prepayment simulator
- Japan Housing Finance Agency: information for current borrowers
Rules and published amounts can change. Open the source pages and confirm the date and conditions before making a tax, payroll, benefits, pension, or investment decision.
Frequently asked questions
Does an extra mortgage payment always reduce the term?
Not necessarily. Lenders can apply prepayments differently, so confirm whether your procedure shortens the term, reduces later payments, or charges a fee.
Does this calculator use today's mortgage rate?
No. It uses only the annual rate you enter from a lender quote or existing loan statement.