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) | ~$123,000 | $72,000 |
| 7% (mid) | ~$156,000 | $72,000 |
| 10% (optimistic) | ~$228,000 | $72,000 |
Investing $300 a month for 20 years means contributing $72,000 of your own money — and at a 7% return, compounding adds around $84,000 on top, growing your balance to roughly $156,000. Twenty years more than doubles your contributions, with compounding adding more than you put in yourself. For many Australian families, $300 a month is a realistic target that over two decades quietly builds a six-figure investment portfolio.
For Australians, $300 a month is a realistic and achievable amount to invest outside of superannuation — roughly what you might direct into a low-cost ETF like VAS or VGS each month via a platform like Pearler or CommSec Pocket. At a 7% average annual return broadly in line with long-run ASX and global index performance, your $72,000 in contributions grows to around $156,000 over 20 years — more than double, with compounding adding more than you contributed yourself. For many Australian families starting in their 30s or 40s, this is a realistic path to a six-figure investment portfolio well before retirement. Tools like Sharesight make it easy to track your actual returns against these projections over time.
Twenty years is where compounding starts outpacing your contributions. Here's how $300 a month plays out across time horizons at a 7% return:
| Time period | Total contributed | Final balance (7%) | Growth from compounding |
|---|---|---|---|
| 10 years | $36,000 | ~$52,000 | ~$16,000 |
| 20 years | $72,000 | ~$156,000 | ~$84,000 |
| 30 years | $108,000 | ~$366,000 | ~$258,000 |
Contributions triple from 10 to 30 years, but compounding growth jumps from $16,000 to $258,000 — more than 16 times. That's the compounding effect accelerating as your balance grows larger.
If $300/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.