Loan Calculator

What is a Loan Calculator?

The loan calculator is a tool that estimates monthly payments and total interest paid based on the loan amount, annual interest rate, and repayment period. It can be used to estimate loans such as mortgages, auto loans, education loans, equipment loans, and personal loans—any situation where a fixed amount is repaid over a set period.With this tool, you can choose between fixed-rate equal principal and interest repayment and equal principal repayment.With the principal-and-interest repayment plan, the basic monthly payment remains roughly constant; the proportion of interest is higher at the beginning of the repayment period, and the proportion applied to the principal increases as repayment progresses. With the principal-only repayment plan, the principal paid each month remains constant, and both the interest and the monthly payment gradually decrease as the outstanding balance decreases. You can view these changes month by month in the repayment schedule.

When considering a loan, it’s important to look not only at your monthly payment but also at the total interest you’ll pay over the life of the loan. Even for the same loan amount, the total interest tends to increase as the interest rate rises or the repayment period lengthens.Conversely, while shortening the repayment period increases your monthly payment, it generally makes it easier to keep interest costs down. This calculator displays the basic monthly payment, total repayment amount, interest paid, and estimated repayment completion date simultaneously, allowing you to compare repayment plans by entering different sets of conditions.

Additionally, users can calculate the effects of making a fixed additional payment each month versus making a one-time additional payment in a specified month. The amount used for the prepayment is treated as an application toward the principal, and the system displays the resulting reduction in interest and the shortened repayment period.For example, you can compare how the pay-off date and total interest change when making small additional payments each month versus making a lump-sum payment during bonus season. Since actual financial institutions have different policies regarding prepayment fees, minimum payment amounts, and repayment methods, be sure to check your contract terms before making a final decision.

You can select from multiple currencies, such as the Japanese yen, U.S. dollar, and euro; however, this tool does not perform currency conversion. The selected currency is used to change the display format of the amounts. Additionally, the loan terms you enter are calculated using JavaScript within the browser and are not sent to the server for calculation.Since loan approvals, taxes, insurance premiums, guarantee fees, administrative fees, variable interest rates, and bonus repayments are not included in the calculations, please use the results from this tool as a rough estimate when planning your repayment schedule.

How to Use

1. Enter the loan amount and select the currency to be used for the amount display.
2. Select either “Equal Principal and Interest Repayments” or “Equal Principal Repayments” as the repayment method.
3. Enter the annual interest rate as a percentage. You can enter 0 to calculate an interest-free loan.
4. Specify the repayment period in years and additional months, and confirm the repayment start date.
5. If necessary, enter the amount of the additional monthly payment or the amount of the one-time additional payment, along with the month in which it will be made.
6. When you click “Calculate Payment,” the monthly payment, total interest, total payment, estimated completion date, and repayment schedule will be displayed.
7. You can switch between "monthly" and "annual" views to view the repayment schedule. If you set up an early repayment, the system will also display the amount of interest saved and the reduction in the repayment period compared to the standard repayment plan.

Calculation Notes

• This is an estimate based on a fixed-rate loan with either equal principal and interest payments or equal principal payments. Variable-rate and stepped-rate loans are calculated differently.
• Actual repayment amounts may vary depending on each financial institution’s rounding rules, repayment dates, pro-rata interest calculations, and fees.
• Guarantee fees, administrative fees, insurance, taxes, late fees, etc., are not included.
• We will calculate this as a method in which the full amount of the prepayment is applied to the principal, and the repayment period is shortened while maintaining the standard repayment amount thereafter.
• This tool is a general-purpose calculator intended for informational purposes only and does not constitute advice regarding loans, investments, or household finances.

Frequently Asked Questions

How do you calculate the monthly loan payment?

With equal principal and interest payments, the basic monthly payment—which remains roughly constant—is calculated based on the principal amount, monthly interest rate, and number of payments. With equal principal payments, the principal is divided equally by the number of payments, and interest is added based on the remaining balance, so the monthly payment gradually decreases.

What is the difference between equal principal and interest payments and equal principal payments?

With equal principal and interest payments, the monthly payment amount remains roughly constant, making it easier to plan. With equal principal payments, the principal paid each month remains constant; while the initial payments are higher, this method tends to result in lower total interest under the same conditions.

Can this also be used to calculate a mortgage?

This can be used to estimate payments for a fixed-rate mortgage with equal principal and interest payments. However, it does not include mortgage-specific items such as guarantee fees, group credit life insurance, tax implications, or variable interest rates.

Can I use it for car loans and education loans as well?

Yes. This can be used as a rough estimate for a typical loan where a fixed amount of principal is repaid monthly at a fixed interest rate. Please check separately for contract-specific fees and repayment terms.

Can I calculate this even with a 0% annual interest rate?

Yes. If you set the annual interest rate to 0, the system will calculate the loan amount by dividing it equally across the number of payments without charging interest.

What changes when I make an early repayment?

Since this tool applies additional payments toward the principal, the interest accrued afterward may decrease, and the time to full repayment may be shortened. It displays the amount of interest saved and the number of months reduced compared to the standard repayment plan.

Can I set up both monthly prepayments and a one-time prepayment at the same time?

Yes. You can set both a monthly additional payment amount and an additional payment amount to be made only once in a specified month.

What can I check in the repayment schedule?

You can view the monthly payment amount, the portion applied to the principal, the interest, the additional payment amount, and the balance after the payment. You can also switch to a yearly summary view.

Will the amount be converted when I change the currency?

No. The currency selection is intended to change the display format of amounts. It is not a feature for converting the loan amount into a different currency.

Can you calculate variable interest rates?

The current calculations are based on the assumption of a fixed interest rate that remains constant throughout the term. They do not support accurate estimates for loans where interest rates may change in the future.

Why do the calculation results differ from the repayment amount provided by the financial institution?

Since actual contracts are subject to specific terms—such as prorated calculations, rounding rules, repayment dates, fees, and insurance premiums—there may be discrepancies compared to estimates based on general formulas.

Are the loan amount and interest rate I entered sent to the server?

No. The calculations are performed within the browser; the loan terms you enter are not sent to the server for calculation.

Is it okay to determine the loan amount based solely on these calculation results?

This tool is intended to provide an estimate of your repayment amount. When making an actual decision about taking out a loan, please consider your income, living expenses, emergency funds, and contract terms, and consult with a financial institution or expert as needed.