Save & Invest · Compounding

Compound Interest Calculator — The eighth wonder of the world.

Watch a starting sum and regular contributions snowball as returns compound year after year.

What you enter

  • Starting amount
  • Monthly contribution
  • Annual return
  • Years
  • Compounding

How this is calculated

Your starting amount and regular contributions grow at the periodic rate implied by your annual return and chosen compounding frequency (monthly, quarterly or annually). Each period the balance earns a return, then the contribution is added. The chart splits the final value into what you put in versus what compounding earned.

Common questions

Does compounding frequency matter much?

Less than people expect. $100,000 at 7% for 20 years ends about 1.5% higher compounded monthly versus annually. The rate, the time and the contributions dominate — frequency is a rounding-level effect.

What return should I assume?

Long-run Australian and global share returns have averaged roughly 7–9% a year before inflation and fees; cash and bonds much less. Whatever you pick, the result is before tax and fees — your actual outcome will be lower by those.

Why is starting early so powerful?

Each year of delay costs you the compounding on all future growth of that year's money. At 7%, money doubles about every 10 years — starting 10 years earlier roughly doubles the final value of every dollar you contribute at the start.

How does it rank?

Once you have your result, see how your number compares against your demographic with our full money rank — by age, sex, state and household composition.

Methodology & data

INDICATIVE · BEFORE TAX & FEES. Australian context, FY 2026–27 tax brackets by default (15% lowest marginal rate from 1 July 2026) with a financial-year selector on tax calculators. Calculations are indicative and based on simplified public models — not personal financial, tax or legal advice. See the full disclaimer.

Primary data sources

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