Interest calculator
Deposit & loan interest calculator
Compare deposit growth with loan interest, including the effect of a recurring monthly extra payment.
Final balance after tax——
| Period | Year-end balance | Cumulative interest |
|---|
Monthly payment estimate——
| Period | Annual payment | Principal | Interest | Ending balance |
|---|
Payoff months
Repayment start month
Regular repayment completion month
Completion month with recurring extra payment
Payoff months are shown.
Compare regular and recurring extra payment
The extra payment is a mathematical estimate added after the regular monthly payment.
| Period | Annual payment | Scheduled principal | Extra principal | Interest | Ending balance |
|---|
Rates vary by institution, product and contract date. This page is a mathematical estimate and does not recommend a product or loan. Recurring extra-payment results assume the same amount is added after each monthly payment; confirm fees, contract terms and actual availability with the lender.
Show calculation trail
Deposit calculations apply the entered annual rate at the selected compounding frequency and add contributions to the before-tax balance.
- Term: —
- Rate: —
- Contributions: —
- Gross interest: —
- Estimated tax: —
- After-tax balance: —
Loan calculations apply the annual rate divided by 12 to each repayment cycle. Fees, guarantees, bonus payments and rate changes are excluded.
- Term: —
- Monthly rate: —
- Method: —
- Payment: —
- Total paid − principal = total interest: —
- Ending balance: —
The displayed formula is an estimate for these inputs and can differ from an actual financial contract.
Compare conditions A and B
Save two deposit or loan conditions and inspect the difference. Data stays in this browser.
| Metric | Condition A | Condition B | Difference |
|---|---|---|---|
| Payoff month | Completion month unavailable. | Completion month unavailable. | Completion month unavailable. |
Inputs that changed
How to read deposit and loan rates
- For deposits, compare compounding frequency, contributions and after-tax receipts as well as the rate.
- For loans, consider total paid and total interest, not only the monthly payment.
- Variable rates, early-repayment fees, guarantees and insurance depend on the contract.
- Share URLs do not include input amounts; the result appears only in the explicit share text.
References: National Tax Agency of Japan / Bank of Japan statistics