Compound interest calculator for Japan
See what regular contributions turn into over time.
Changing country switches the currency and resets the inputs to local starting values.
Your numbers
Balance after 25 years
￥69,343,504
￥45,343,504 of it is growth
- Total contributed
- ￥24,000,000
- Interest earned
- ￥45,343,504
- Growth multiple
- 2.89×
- final balance ÷ money in
- Average growth per year
- ￥1,813,740
Balance
by year| Period | Contributed | Growth | Balance |
|---|---|---|---|
| Year 3 | ￥4,200,000 | ￥644,146 | ￥4,844,146 |
| Year 6 | ￥6,900,000 | ￥2,067,229 | ￥8,967,229 |
| Year 9 | ￥9,600,000 | ￥4,450,684 | ￥14,050,684 |
| Year 12 | ￥12,300,000 | ￥8,018,205 | ￥20,318,205 |
| Year 15 | ￥15,000,000 | ￥13,045,592 | ￥28,045,592 |
| Year 18 | ￥17,700,000 | ￥19,872,886 | ￥37,572,886 |
| Year 21 | ￥20,400,000 | ￥28,919,330 | ￥49,319,330 |
| Year 24 | ￥23,100,000 | ￥40,701,822 | ￥63,801,822 |
| Year 25 | ￥24,000,000 | ￥45,343,504 | ￥69,343,504 |
Returns are assumed constant and gross of tax. Real markets are lumpy, so treat this as a trend line rather than a forecast.
How to read the result
Compounding is unremarkable for the first few years and then does almost all of the work at the end. Most people underestimate the back half badly.
Set a starting balance, a monthly contribution and a rate, and the projection below splits the final number into what you put in versus what the growth added.
This page is set to Japan and prints JPY. Starts at a 0.3% deposit return. Every figure is a starting point you should overwrite with your own.
Worked example in JPY
Using the values the form starts with.
Balance after 25 years
￥69,343,504
- Total contributed
- ￥24,000,000
- Interest earned
- ￥45,343,504
- Growth multiple
- 2.89×
- Average growth per year
- ￥1,813,740
Questions people ask
- Monthly or annual compounding?
- This model compounds monthly and adds your contribution at the end of each month, which matches how most brokerage and savings accounts behave.
- What rate should someone in Japan use?
- For a broad global equity index, 6–8% before inflation is a common planning assumption anywhere. For cash, use your local deposit rate — around 0.3% in Japan at the moment.
- Does this account for tax?
- No. Tax-sheltered accounts exist in most countries and change the outcome materially, so compare the gross figure here against your own account rules.
Compound interest in other countries
Same maths, local currency and local starting values.