Money
Investment Return Calculator
Enter your principal, annual return rate, investment period, and compounding frequency to simulate future value. See how compound interest grows your money year by year.
| Principal |
JPY
|
|---|---|
| Annual Return Rate |
%
|
| Investment Period |
years
|
| Compounding Frequency |
| Year | Balance | Gain | Return Rate |
|---|---|---|---|
| {{ row.year }} | {{ fmt(row.balance) }} | {{ fmt(row.gain) }} | +{{ fmtRate(row.gainRate) }}% |
How much does ¥1,000,000 grow? (Monthly compounding)
Future value of ¥1,000,000 at various rates and periods (monthly compounding, before tax).
| Period \ Rate | 1% | 3% | 5% | 7% | 10% |
|---|---|---|---|---|---|
| 1years | 1,010,046 | 1,030,416 | 1,051,162 | 1,072,290 | 1,104,713 |
| 5years | 1,051,249 | 1,161,617 | 1,283,359 | 1,417,625 | 1,645,309 |
| 10years | 1,105,125 | 1,349,354 | 1,647,009 | 2,009,661 | 2,707,041 |
| 20years | 1,221,301 | 1,820,755 | 2,712,640 | 4,038,739 | 7,328,074 |
| 30years | 1,349,690 | 2,456,842 | 4,467,744 | 8,116,497 | 19,837,399 |
Tips
- Switching compounding from annual to monthly increases your final balance slightly. The more frequent the compounding, the greater the benefit (daily > monthly > annual).
- A 5–7% annual return is a rough historical average for index funds (e.g. S&P 500). Past performance does not guarantee future results.
- Rule of 72: Divide 72 by the annual rate to estimate how many years it takes to double your money. At 5% that's ~14.4 years; at 7% it's ~10.3 years.
- The longer the investment period, the faster compound growth accelerates. Extending from 10 to 20 years often more than doubles the gains — time is your greatest asset.
Frequently Asked Questions
Side Note — The Rule of 72 and the Mystery of Compound Interest
The Rule of 72 is a simple mental-math shortcut: divide 72 by the annual rate to find roughly how many years it takes to double your money. At 3% that's 24 years; at 5%, 14.4 years; at 10%, just 7.2 years. Records of compound interest calculations survive on Babylonian clay tablets, making the concept almost as old as written history itself.
The counterintuitive part of compound growth is how it accelerates over time. ¥1,000,000 at 5% per year grows to ~¥1.63M after 10 years, ~¥2.65M after 20 years, and ~¥4.32M after 30 years. The second ten years add ¥1.02M, but the third ten years add ¥1.67M — the same time span produces more than 60% more gain. This is why starting early matters so much more than investing more.