Enter the conditions
yen
/mo
%
years
Future value
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Growth (year by year)
| Year | Contributed | Gain | Value |
|---|
How to use the compound interest calculator
"If I save ¥30,000 a month at 3% for 20 years, how much will I have?" Enter an initial amount, contribution, return and term to project the outcome with compound interest. It separates total contributions from gains and shows a yearly view.
How to use it
Enter the initial amount, monthly contribution, assumed annual return and term. Because compound interest earns interest on interest, the share of gains grows over longer periods. Try different returns to feel the effect of long-term investing.
Reading the result
This tool assumes a constant return and excludes taxes and fees. Real investments fluctuate and can lose principal. It does not guarantee future results, so use it only as a guide.
Frequently asked questions
What is compound interest vs simple interest?+
Compound interest earns interest on interest, so over long periods it grows more than simple interest, which earns only on the principal.
This tool compounds monthly.
This tool compounds monthly.
How is the future value calculated?+
With monthly rate = annual / 12, the initial amount compounds monthly and each monthly contribution is added at month end.
At 0% it equals the total contributions.
At 0% it equals the total contributions.
Does the contribution timing change the result?+
Yes. This tool assumes contributions at month end; contributing at the start of the month grows slightly more.
Use it as a guide.
Use it as a guide.
Are taxes and fees included?+
No. Taxes on gains and fees such as expense ratios are not included.
It assumes a constant rate, and real returns vary.
It assumes a constant rate, and real returns vary.
Are my inputs stored?+
No. All calculation happens in your browser, and the values you enter are never sent to or stored on a server.
Formula
・Future value = initial × (1+i)ⁿ + monthly × ((1+i)ⁿ − 1) / i (i = monthly rate = annual/12, n = months = years×12, end-of-period)
・At 0% rate = initial + monthly × n
・Total contributions = initial + monthly × n / Gain = future value − contributions
・An estimate assuming a constant rate, no taxes/fees and month-end contributions; based on the standard future-value / annuity formula.
・Future value = initial × (1+i)ⁿ + monthly × ((1+i)ⁿ − 1) / i (i = monthly rate = annual/12, n = months = years×12, end-of-period)
・At 0% rate = initial + monthly × n
・Total contributions = initial + monthly × n / Gain = future value − contributions
・An estimate assuming a constant rate, no taxes/fees and month-end contributions; based on the standard future-value / annuity formula.
Please note
This site does not represent any financial institution and does not solicit any product or provide investment advice. The result does not guarantee future returns. Real investments fluctuate and may lose principal, and taxes and fees apply. Make investment decisions at your own responsibility.
This site does not represent any financial institution and does not solicit any product or provide investment advice. The result does not guarantee future returns. Real investments fluctuate and may lose principal, and taxes and fees apply. Make investment decisions at your own responsibility.