Compound Interest Calculator
See how your money grows over time with compound interest. Includes regular contributions, inflation adjustment, and a visual breakdown of contributions vs interest earned.
The Power of Compound Interest
Compound interest means you earn interest on your interest — not just your original investment. Over long time periods, this creates exponential growth. A $10,000 investment at 7% p.a. doubles every ~10 years to $20k, then $40k, then $80k.
Adding regular contributions supercharges this effect. Even $200/month added to a $10,000 investment at 7% for 30 years produces over $260,000 — from just $82,000 actually invested.
Frequently Asked Questions
Compound interest is interest earned on both your original principal and previously accumulated interest. It creates exponential growth over time — the longer you invest, the faster it accelerates.
Use the Rule of 72 — divide 72 by your annual return. At 6%, money doubles in approximately 12 years. At 8%, 9 years. At 10%, just over 7 years. Starting early is far more powerful than investing more later.
Options include high-interest savings accounts (4-5% p.a.), ETFs and index funds (historically 7-10% p.a.), and superannuation. Higher returns come with higher risk. Consider speaking with a financial adviser.
How Compound Interest Works
Compound interest is interest on interest — you earn returns not just on your original investment, but on all previous gains too. Einstein reportedly called it “the eighth wonder of the world.” Starting early is the single biggest factor in long-term wealth building.
at 7% p.a.
at 7% p.a.
at 7% p.a.
Compound Interest Formula
Where: A = final amount | P = principal | r = annual rate (decimal) | n = compounds per year | t = years
Most Australian savings accounts compound daily or monthly. Superannuation returns compound annually. The calculator above handles all of this automatically.
Returns shown are illustrative. Investment returns are not guaranteed and will vary. Not financial advice.