Compounding works best with time, consistency, and low friction. These common mistakes quietly reduce outcomes.
Model the impact in Money GrowthTime is the single most valuable ingredient in compound interest — and it's the one you can't buy back. Consider two investors both investing $500 a month at 7% returns: one starts at 25 and stops at 35 (10 years, $60,000 contributed), the other starts at 35 and invests until 65 (30 years, $180,000 contributed). The early starter often ends up with more at 65, despite contributing three times less money. Every year you wait costs you not just that year's contributions, but all the future compounding that money would have generated. The best time to start was yesterday. The second best time is today.
Many investors stop contributing during market downturns — exactly the wrong time to pause. When markets fall 20%, you're buying units at a 20% discount. Stopping contributions during a downturn locks in the loss and misses the recovery. The investors who consistently contributed through the 2008 GFC and the 2020 COVID crash ended up significantly ahead of those who paused and waited for "certainty." Automate your contributions so they happen regardless of what markets are doing that week.
Fees compound against you just as returns compound for you. A 1% annual management fee sounds small, but over 30 years it can reduce your final balance by 20-25%. On a $500,000 portfolio, that's $100,000+ quietly disappearing into management costs. For Australian investors, low-cost index ETFs like VAS (0.07% pa) and VGS (0.18% pa) make this a solvable problem — but many investors still hold managed funds charging 1-2% pa without realising the long-term cost. Use the calculator to model a 7% return vs a 6% return over 30 years to see how much a 1% fee difference costs you.
Building your retirement plan around 10% annual returns and then experiencing 6-7% actual returns can leave you significantly short. The long-run average return of the Australian share market (ASX 200) including dividends has been around 9-10% pa historically — but this includes reinvested dividends and varies enormously by period. After fees, tax and inflation, real returns are considerably lower. Always build your primary plan on conservative assumptions (5-6% nominal) and treat the optimistic scenario as a bonus, not a baseline.
Dividend reinvestment is where a huge portion of long-term returns come from. For Australian ETFs like VAS, dividends (including franking credits) can add 4-5% pa on top of price growth. If you're spending those dividends rather than reinvesting them, you're effectively withdrawing from your portfolio during the accumulation phase. Most ETF platforms and brokers offer dividend reinvestment plans (DRPs) that automatically buy more units with each distribution — set this up and leave it running.
Investors who check their portfolio daily are more likely to make emotional decisions — selling during dips, chasing recent winners. Research consistently shows that less frequent portfolio monitoring leads to better long-term outcomes. Set up a quarterly or annual review schedule, automate contributions, and resist the temptation to react to short-term market noise. The calculator is a planning tool, not a market predictor — use it to set your plan, then let compounding do its job.
Waiting to start is usually the biggest, because time can’t be replaced.
Run two scenarios in /grow.html: start now vs start 5 years later with the same contribution.
Over long periods, fees can reduce outcomes a lot. Try lowering the return rate slightly to approximate fees.
If you can, do both. If you must choose, extra time often beats extra contribution.
See /how-compound-interest-works.html.