A lump sum gets more time in the market, but results still depend on your return assumptions. Compare conservative, mid, and optimistic scenarios.
Open the Money Growth Calculator| Return rate | Final balance | Amount invested |
|---|---|---|
| 5% (conservative) | ~$53,100 | $20,000 |
| 7% (mid) | ~$77,400 | $20,000 |
| 10% (optimistic) | ~$134,500 | $20,000 |
Investing $20,000 as a one-off lump sum for 20 years shows just how transformative two decades of compounding can be. At a 7% return your $20,000 grows to around $77,400 — nearly four times your original investment with no further contributions. At 10% it reaches $134,500, turning a single $20,000 deposit into a six-figure sum. For Australians who invest a $20,000 windfall in their 40s and leave it untouched, this could be worth between $77,000 and $134,000 by retirement — a compelling reason to invest rather than spend.
If you have the money ready now, investing earlier gives compounding more time. Waiting in cash can reduce long‑term growth (but may reduce short‑term risk).
If investing everything at once feels risky, model a smaller lump sum plus monthly contributions. You’ll see the tradeoff between time invested and timing risk.
Often lump sum wins mathematically because money is invested sooner, but behaviour and timing risk matter.
Try 5% (conservative), 7% (mid), 10% (optimistic) to see a range.
No. Treat results as estimates. You can lower the assumed return rate to be conservative.
If the timeline is short, a stable savings option may be safer. Consider using the ETF vs Savings comparison.
See /how-compound-interest-works.html.