Compound Interest & Savings Growth Calculator

Compound interest means you earn returns on your returns. Each period, your gains are added to your balance and the next period’s returns are calculated on the larger amount. Over decades, this creates exponential growth — often called the eighth wonder of the world.

For a diversified global or Australian equity index fund, 7–10% is the commonly cited long-term annual return. Using 7% (roughly inflation-adjusted) gives a more conservative and realistic picture of real purchasing power over time.

Divide 72 by your annual return to estimate how long it takes to double your money. At 7%: 72 ÷ 7 ≈ 10 years. At 10%: ~7 years. At 4%: ~18 years. It’s a quick mental shortcut for comparing investment options.

No — results are in nominal (not inflation-adjusted) terms. To estimate real value, subtract the inflation rate from your return. If markets return 9% and inflation is 3%, enter 6% for a real purchasing-power projection.

More frequent compounding produces slightly higher returns. Monthly compounding on $10,000 at 7% over 10 years produces ~$20,097 vs ~$19,672 with annual compounding. The difference grows with time and balance size.

Yes — enter your current super balance as the initial investment, your monthly employer contribution (salary × super rate ÷ 12) as the monthly contribution, and 7% as the long-term return. For a more detailed super-specific projection, try our Superannuation Calculator.