Everyday
Compound Interest Calculator
Calculate a future value and the interest from a principal, annual rate, and period in years. You can add monthly deposits. This is not tax or product advice.
Result
Future value
101,202JPY
Gained from compound interest1,202JPY
- Principal
- 100,000JPY
- Deposits over the whole period
- 0JPY
- Money you put in
- 100,000JPY
No deposits in this period.
Each month uses one twelfth of the annual rate. Fractional yen are rounded down, then the deposit is added.
Monthly compound interest
See a future value and the interest earned from a principal, an annual rate, and a period in years. You can also add monthly deposits.
How the calculation works
One year is 12 months. Each month uses one twelfth of the annual rate on the current balance, and fractional yen are rounded down before a deposit is added.
A 0% rate earns no interest, so the balance grows only by the deposits you enter. A period of 0 years returns the principal alone.
This is a yen estimate. It does not include tax, fees, or a recommendation to buy a product.
Frequently asked questions
Is this investment advice?
No. It estimates compound interest only. It does not cover taxes, fees, or product recommendations.
How are fractional yen handled?
Fractional yen are rounded down and are not carried into the next month.
When is a deposit added?
After that month’s interest. The count covers the whole period, not a single year. One year allows up to 12 deposits, and three years allow up to 36.
What happens at 0% or for 0 years?
A 0% rate earns no interest. A period of 0 years returns the principal only, with no deposits and no interest.
Are the amounts and rate I enter saved?
No. The calculation runs in your browser, and the amounts and rate are not sent to a server.