Run 3 return-rate scenarios to see a realistic range of outcomes — then adjust your monthly amount until it fits your budget.
Open the Money Growth Calculator| Return rate | Final balance | Total contributed |
|---|---|---|
| 5% (conservative) | ~$16,000 | $12,000 |
| 7% (mid) | ~$17,000 | $12,000 |
| 10% (optimistic) | ~$20,000 | $12,000 |
Investing $100 a month for 10 years means contributing $12,000 of your own money — and at a 7% return, compounding adds around $5,000 on top, growing your balance to roughly $17,000. Ten years at this level is a modest but meaningful start — the real power comes from keeping going. Think of this as building the habit first; the numbers grow significantly if you extend to 20 or 30 years.
For Australians, $100 a month is the most accessible entry point for regular investing outside of superannuation — less than $25 a week directed into a low-cost ETF like VAS or VGS. At a 7% average annual return broadly in line with long-run ASX and global index performance, your $12,000 in contributions grows to around $17,000 over 10 years. The numbers are modest at 10 years, but this is really about building the habit — and the compounding effect grows dramatically if you keep going. A tool like Sharesight makes it easy to track your actual returns from the very beginning, however small the portfolio.
$100 a month at 10 years is just the start. Here's what the same habit produces over longer timeframes at a 7% return:
| Time period | Total contributed | Final balance (7%) | Growth from compounding |
|---|---|---|---|
| 10 years | $12,000 | ~$17,000 | ~$5,000 |
| 20 years | $24,000 | ~$52,000 | ~$28,000 |
| 30 years | $36,000 | ~$122,000 | ~$86,000 |
Contributions triple from 10 to 30 years, but compounding growth jumps from $5,000 to $86,000. The habit you build at 10 years becomes the foundation for everything that follows.
If $100/month feels hard right now, test a smaller starting amount and increase it each year. Even small step-ups can move the result a lot over long horizons.
It can be. The biggest drivers are consistency and time. Use the calculator to compare multiple return scenarios.
Try 5% (conservative), 7% (mid), and 10% (optimistic) to see a range.
No. Treat results as estimates. You can lower your assumed return rate to be conservative.
If you can’t do both, extra time often helps a lot. Then increase contributions over time.
See /how-compound-interest-works.html.