Loan Repayment Calculator (Equal Monthly Payment)
＋More features: prepayment and a comparison of repayment methods
Both use the loan terms from the form above (amount, rate and term) as they are.
Prepayment simulation (term-shortening type)
Keeps the monthly payment the same and calculates how much interest you save by paying a lump sum after a given number of years, finishing the loan earlier.
If you chose equal-principal repayment instead
Compares with “equal-principal repayment” (元金均等), where the first payments are larger but the total interest is smaller.
Just enter the amount, rate and term to see how much you would repay each month on a home loan or car loan in Japan, along with the total repayment and total interest. It uses the equal-payment method (元利均等返済) that Japanese banks use by default, so it is a quick check of “how heavy would the monthly payment be?” before you borrow.
How to use
- Enter the loan amount in man-yen (for 30,000,000 yen, enter “3000”).
- Enter the annual interest rate (%) and the repayment term (years).
- The monthly payment, total repayment and total interest appear as you type — no button needed.
How it is calculated
It uses the standard formula for equal-payment repayment (元利均等返済) — the most common method in Japan, where the monthly payment stays constant.
- Monthly payment = loan amount × r × (1+r)ⁿ ÷ ((1+r)ⁿ − 1)
r = annual rate ÷ 12 (monthly rate), n = term × 12 (number of payments). At 0% it is loan amount ÷ n. - Total repayment = monthly payment × number of payments / Total interest = total repayment − loan amount
- Example: 30,000,000 yen (3,000 man-yen) at 1.5% a year over 35 years → about 91,855 yen a month, about 38,580,000 yen in total
Sources and assumptions
- The above is the general mathematical definition of equal-payment repayment (the monthly payment is rounded to the nearest yen, and the total is that monthly payment × the number of payments).
- For the basics of a loan, such as the difference between equal-payment and equal-principal repayment, see the explanations from financial institutions and public bodies.
Assumptions and notes
- It assumes a fixed rate, no bonus-month payments and no prepayment. With a variable rate, future payments will change.
- If you choose equal-principal repayment (a constant principal each month), the first payment is larger than this calculation and then decreases.
- For how much you can borrow and for screening, consult your financial institution.
Frequently asked questions
What is the difference between equal-payment and equal-principal repayment?
Equal payment (this tool) keeps the monthly payment constant, which makes household budgeting easier. Equal principal keeps the principal portion constant: the early payments are larger, but the total interest is smaller.
How much difference does 0.1% in the rate make?
For 30,000,000 yen over 35 years, 1.5% a year (91,855 yen a month) versus 1.6% a year (93,332 yen a month) is about 1,500 yen a month and about 620,000 yen over the whole term. You can calculate both here and compare.
Can it handle bonus-month payments or prepayment?
Bonus-month payments are not supported. For simulations with bonus payments, prepayment or variable rates, use the estimate tool of your financial institution.