Why compounding feels slow and then sudden
Compound growth is exponential, so almost all of the visible progress happens late. Contributing $500 a month at 7% for 25 years produces roughly $460,000 — but the balance passes $100,000 only around year 9 and adds its final $100,000 in the last four years alone. People who abandon investing after five "disappointing" years quit precisely before the part that matters.
Time beats amount
Someone investing $300 a month from age 25 to 65 at 7% ends with roughly $790,000. Someone investing $600 a month from 35 to 65 ends with roughly $735,000 — despite contributing about $72,000 more in total. The first investor's advantage is entirely the extra decade of compounding. This is the strongest argument for starting with an imperfect amount rather than waiting for a perfect one.
Inflation is the number people forget
A $1,000,000 balance in 30 years, at 2.5% inflation, buys what about $477,000 buys today. Always look at the inflation-adjusted figure when setting a target. The same logic applies to your contribution: increasing it in line with your pay rises is what keeps the plan real rather than nominal.
Fees compound too
A 1% annual fee does not cost 1% — over 30 years it typically consumes 20–25% of the final balance, because the fee is charged on the growing balance every year. The gap between a 0.03% index fund and a 1.0% managed product on a $500,000 portfolio is enormous over a working lifetime. This is the one variable in the whole exercise that you fully control.
Where to hold the money
- Employer 401(k) up to the match — an immediate 50–100% return, unbeatable by anything else here.
- Roth or traditional IRA — tax-free growth or a deduction today, depending on which you expect to serve you better.
- Taxable brokerage — no contribution limits, full liquidity, but dividends and realised gains are taxed.
- High-yield savings — for anything you need within about five years, where market volatility is a risk rather than an opportunity.
The realistic caveat
This calculator assumes a constant return. Real markets deliver that average through a sequence of gains and losses, and the order matters — particularly near retirement, when a large drawdown in the first few withdrawal years does lasting damage. Treat the output as a planning midpoint, not a forecast.