Why the curve bends upward
Compound interest pays interest on your interest. In year one that's trivial; by year twenty it dominates — which is why the standard advice is boring and correct: time in the market beats timing the market. $10,000 with $500 a month at 7% becomes about $106,600 in ten years, but roughly $506,000 in twenty-five — the last decade alone adds more than the first fifteen years combined.
Reading your result honestly
The projection assumes a smooth constant return; real investments wobble around their average, and savings account rates move with the RBA. Two things this calculator deliberately leaves out: tax (interest is taxed at your marginal rate outside super — one reason super's 15% is attractive for long horizons) and inflation (subtract roughly 2.5% from the return to think in today's dollars). For the super version with employer contributions built in, use our retirement calculator.