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Compound growth: why time beats timing

A small start growing into a leafy snowball over years.

A small start that grows if you give it years. Time beats guessing the perfect week.

Compound growth is the “interest on interest” (or returns on returns) idea. You earn returns on what you put in and on returns you’ve already earned. Over long stretches, that snowball can get surprisingly chunky, which is why starting earlier often matters more than guessing the perfect week to buy.

MoneySmart puts it simply for savings: the sooner you start and the more regularly you add, the more compounding can work. Same broad idea applies when investments earn returns over many years with a big caveat: investment returns aren’t fixed like a bank rate, and balances can fall.

Time > perfect timing (usually)

Waiting for the “best” day to invest is a classic trap. Markets bounce. Nobody reliably calls every dip. For many long-term investors, a steady habit (regular contributions) beats trying to outsmart every headline: again, not a guarantee, just a calmer approach.

You don’t need a huge paycheck to start exploring the idea. Even small, regular amounts (if they’re money you can leave invested for years) can illustrate how time does heavy lifting.

Illustrative example (not a forecast)

Assumptions: weekly $75 (~$3,900/year); start $0; constant 7% nominal illustrative; end-of-year contributions FV = PMT × (((1 + r)^n − 1) / r); no fees, tax, or withdrawals. Not a prediction.

Start early vs later (same finish age):

  • Early: $75/wk × 30y (18→48) → put in ~$117k → illustrative balance ~$368,400
  • Later: $75/wk × 20y (28→48) → put in ~$78k → illustrative ~$159,900

Growth vs contributions alone (early path):

  • Y10: contrib $39k vs with growth ~$53.9k
  • Y20: $78k vs ~$159.9k
  • Y30: $117k vs ~$368.4k

At illustrative 5% for 30y / $75/wk ≈ ~$259,100.

Chart 1. Early vs late by age (18–48)

Started at 18 vs 28: $75/week to age 48

Age 48: started-at-18 $368,397 · started-at-28 $159,882. Same finish line, different start. Illustrative.

Assumptions
  • Start $0. Weekly amount × 52 treated as an end-of-year contribution.
  • Constant 7% nominal illustrative growth (Chart 3 uses the same idea for $50 vs $100/week).
  • Formula: FV = PMT × (((1 + r)^n − 1) / r). No fees, tax, or withdrawals.
  • Nearest Australian dollar. Not a prediction.

Illustrative only. Assumes constant annual growth and end-of-year contributions. Not a forecast. Past performance ≠ future. Markets go down as well as up.

Chart 2. Years 0–30: with 7% vs contributions only

With 7% illustrative growth vs contributions only

Assumptions
  • Start $0. Weekly amount × 52 treated as an end-of-year contribution.
  • Constant 7% nominal illustrative growth (Chart 3 uses the same idea for $50 vs $100/week).
  • Formula: FV = PMT × (((1 + r)^n − 1) / r). No fees, tax, or withdrawals.
  • Nearest Australian dollar. Not a prediction.

Illustrative only. Assumes constant annual growth and end-of-year contributions. Not a forecast. Past performance ≠ future. Markets go down as well as up.

Chart 3. $50 vs $100 a week over 20 years

$50 vs $100 a week over 20 years

Assumptions
  • Start $0. Weekly amount × 52 treated as an end-of-year contribution.
  • Constant 7% nominal illustrative growth (Chart 3 uses the same idea for $50 vs $100/week).
  • Formula: FV = PMT × (((1 + r)^n − 1) / r). No fees, tax, or withdrawals.
  • Nearest Australian dollar. Not a prediction.

Illustrative only. Assumes constant annual growth and end-of-year contributions. Not a forecast. Past performance ≠ future. Markets go down as well as up.

Live in the now too. Compounding doesn’t demand two-minute noodles forever.

Educational only, not personal financial advice. This content is general information for young Australians learning about money. It does not take into account your objectives, financial situation or needs. Markets go up and down. Past performance is not a reliable indicator of future performance. Growth examples are illustrative only, not forecasts. DoshHero does not recommend any specific share, ETF, crypto asset, property, SMSF, app or product. Before you invest or act on tax matters, check MoneySmart, the ATO, and consider speaking with a licensed financial adviser if you need advice for your situation.