A starting balance, a regular contribution and a rate of return, projected forward. This shows what the balance becomes and where it came from.
The useful part is the split. Over a long enough period the growth exceeds everything you put in, and seeing the crossover is more persuasive than being told it happens.
Shows how a balance grows over time with regular deposits and compounding interest.
Annual rate
The return you assume. This is the input that carries all the uncertainty — a projection over decades is extraordinarily sensitive to it, so try a range rather than a single figure.
Contribution frequency
How often you add to the balance. More frequent contributions of the same annual total finish slightly ahead, because each dollar is invested for longer.
Total contributed is what you put in. Growth is the rest. Early on, contributions dominate; later, growth does, and the point at which they cross is worth noting.
Change the term and re-run. The final balance is not linear in time — the last decade of a thirty-year projection typically adds more than the first two combined, which is the entire argument for starting early.
Change the rate by one percentage point and re-run. The sensitivity is large enough to be uncomfortable, and understanding that is more valuable than any single projection.
Every figure below is computed by the same calculator on this page, from the inputs described. Nothing here is typed in by hand, so an example cannot disagree with the tool.
Compare growth against total contributed. Over this horizon growth is the larger of the two, and that reversal is what compounding is.
Contributions still dominate. Compounding needs time before it does the heavy lifting, and ten years is not enough for it to overtake what you put in.
The annual rate is converted to the contribution period. Each period the balance earns at that rate and the contribution is added.
Growth is the final balance less the starting balance and all contributions.
A constant rate of return
Real returns vary year to year and can be negative. A constant rate is a simplification that produces a smooth curve where reality is jagged, and the sequence of returns matters for anyone drawing down.
No tax and no fees
Investment earnings are generally taxable outside superannuation, and fees reduce returns. A 7% return with 1% of fees compounds like 6%, and over thirty years the difference is very large.
No inflation adjustment
The result is in nominal dollars. Over thirty years inflation substantially reduces what a given amount buys.
It is a projection, not a prediction
The output is exactly as reliable as the rate you entered, which is a guess about decades of markets.
It does not model drawdown
Accumulation and retirement drawdown behave differently, and the order returns arrive in matters far more once you are withdrawing.
Works out how long a savings target takes to reach at your current rate of saving.
Works out how much to set aside each period to reach a savings target by a deadline.
Works out the interest and maturity value on a term deposit, with interest reinvested or paid out at maturity.
Estimates what holding a balance in a full offset account saves in interest, and how much sooner the loan closes if repayments stay the same.
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