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) | ~$41,000 | $24,000 |
| 7% (mid) | ~$52,000 | $24,000 |
| 10% (optimistic) | ~$76,000 | $24,000 |
Investing $100 a month for 20 years means contributing $24,000 of your own money — and at a 7% return, compounding adds around $28,000 on top, growing your balance to roughly $52,000. That's more than double your contributions, with compounding doing as much work as you did over those two decades. For many Australians $100 a month is very achievable, and over 20 years it quietly builds a $50,000+ nest egg from what feels like a small regular commitment.
For Australians, $100 a month is one of the most accessible entry points for regular investing outside of superannuation — less than $25 a week redirected 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 $24,000 in contributions more than doubles to around $52,000 over 20 years. It's a compelling demonstration of compounding doing as much work as you did — adding nearly $28,000 on top of your contributions. For Australians starting young, even $100 a month builds a meaningful supplement to super over a working lifetime. A tool like Sharesight makes it simple to track your actual returns against these projections.
Twenty years is when compounding starts matching your contributions dollar for dollar. Here's how $100 a month plays out across time horizons 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 | ~$114,000 | ~$78,000 |
Contributions triple from 10 to 30 years, but compounding growth jumps from $5,000 to $78,000. That's the power of giving compound interest more time to work.
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.
Keep exploring — these pages connect directly to calculators so you can run your own numbers.