Enter the loan conditions
Amortization schedule (yearly)
| Year | Paid | Principal | Interest | Balance |
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How to use the loan calculator, and how repayments really add up
On a mortgage or car loan, a fraction of a per cent in interest can change the total repaid by a very large amount. Enter the amount borrowed, the annual rate and the term, and this tool returns the monthly payment, the total repaid and the total interest.
How to use it
Enter principal, annual interest rate and term in years. The calculation uses equal-instalment repayment (a fixed monthly payment) with no bonus payments. Re-running it with slightly different rates is a quick way to judge an offer or a refinancing decision.
Equal instalments vs. equal principal
Equal instalment repayment — the most common form in Japan — keeps the monthly payment constant, which makes budgeting easy. Early payments are mostly interest, so the balance falls slowly at first. Equal principal repayment pays down a fixed slice of principal each month: payments start higher but the balance drops faster and the total repaid is lower, sometimes by a substantial margin on the same terms.
What one percentage point costs
Borrowing 30 million yen over 35 years at 1.0% means roughly 85,000 yen a month and about 35.6 million repaid. At 2.0% it becomes roughly 99,000 a month and about 41.7 million — over 6 million yen for one percentage point. The longer the term and the larger the principal, the more the rate matters.
How overpayments work
An overpayment can either shorten the term or reduce the monthly payment. Shortening the term saves far more interest, and the earlier it is made the better, because it removes the interest that would have accrued over all the remaining years. The caveat is liquidity: keep an emergency fund rather than putting every spare yen into the loan.
What you can borrow is not what you can afford
Approval is not affordability. Japan's Housing Finance Agency sets its Flat 35 criteria at 30–35% of gross annual income, but that is the ceiling a lender will accept, not the amount you can comfortably repay. Take-home pay is only about 75–80% of gross, and the criteria take no account of school fees or running a car. A safer working guide is keeping annual repayments within 20–25% of take-home pay. Budget for the costs a loan calculator cannot see either — property tax, maintenance and insurance on a home; inspections, insurance and parking on a car. For the saving side, see the compound interest calculator.
Frequently asked questions
How is the monthly payment calculated?+
At 0% it is P / n.
What is the difference from an equal-principal loan?+
This tool uses the equal-payment method.
Can it handle extra or lump-sum payments?+
Use it for a basic monthly-repayment estimate.
Will the figures match my actual payments?+
This is an estimate assuming a fixed rate and no fees.
Are my inputs stored?+
・Monthly payment (equal instalment) = P × r × (1+r)ⁿ ÷ ((1+r)ⁿ − 1), where P = principal, r = monthly rate = annual ÷ 12, n = number of payments
・At 0%: P ÷ n. Total repayment = payment × n; total interest = total − P
・An estimate assuming a fixed rate, no fees, no bonus payments and equal monthly instalments.
・Equal-principal repayment costs more early but less in total (this tool uses equal instalments).
・Japan Housing Finance Agency, Flat 35 debt-to-income criteria: annual repayments within 30% of gross annual income below 4 million yen, or 35% at or above it
・Financial Services Agency, Japan. Basic guide to finance: the importance of checking a repayment plan before borrowing
This site does not represent any financial institution and does not solicit or advise on loans. It does not guarantee accuracy, and actual screening, rates, fees, guarantee costs and payments will differ. Always confirm the lender's formal terms before signing.