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Compound Growth Illustrator

An educational illustration of how compound returns and regular contributions can grow a balance over time. Change the assumptions, see what moves. Not financial advice.

Final balance
Total contributed
Total growth
Assumption — not a prediction
Reduces effective return
This is an educational illustration, not a prediction. It shows how compound growth works using the assumptions you entered — actual returns vary, are not guaranteed, and your circumstances are not considered here. This is not financial advice.

How compound growth works

Compound growth is what happens when the returns on an investment are themselves reinvested — so that each period, gains are calculated on a growing base rather than the original amount. Growth generates growth. Over long periods this creates a curve rather than a line: the balance accelerates because you are earning returns on returns, not just on what you originally put in.

The chart above separates the two components. The lower band is contributions — the money put in. The upper band is growth. At the start, contributions dominate. Over time, if the return rate is meaningful, growth can come to dwarf contributions entirely.

Why time is the primary variable

An investment made today has more compounding periods than the same investment made in five years — and those additional periods act on an ever-larger base. This is the mechanical reason why "starting earlier" is so consistently noted in discussions of long-term savings. The effect is not linear: the later you start, the more compounding periods you lose, and those lost periods compound their own absence.

The role of regular contributions

Each periodic contribution begins its own compounding journey. The first has the longest runway; later contributions have shorter ones. Together, regular contributions produce a cumulative effect that grows over time.

Fees and the effective return rate

A fee reduces the effective return rate. A 6% return with a 1.5% annual fee produces the same mathematical outcome as a 4.5% fee-free return. Because this reduction compounds, small differences in fee levels have a material long-term impact — proportionally larger than the fee percentage itself suggests.

Effective per-period rate = (annual return % − annual fee %) ÷ 100 ÷ periods per year
Each period: balance = balance × (1 + rate) + contribution
Growth = final balance − (starting balance + all contributions)

What this illustration assumes

This calculator assumes a constant annual return rate and a fixed contribution amount — two simplifications that real investments do not provide. Actual returns fluctuate; contributions may change. Inflation is not accounted for, so figures are in nominal terms. Taxes on returns are not modelled. For projections based on your circumstances, speak to a licensed financial adviser.

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