Lever 1: Start 5 Years Earlier
The single highest-leverage action in compound interest is time. Adding 5 years to the beginning of an investment period has a dramatically larger effect than adding 5 years to the end.
Impact of 5-year earlier start on compound growth — $500/month at 7%
| Start Age | $500/Month at 7% | Balance at 55 | Balance at 60 | Balance at 65 |
|---|---|---|---|---|
| 25 years old | $697,000 | $984,000 | $1,369,000 | |
| 30 years old | $455,000 | $654,000 | $917,000 | |
| 35 years old | $284,000 | $415,000 | $588,000 |
Lever 2: Increase Contributions by $100/Month
Adding $100/month to your contributions sounds small. Over 30 years at 7%, that additional $100/month generates an extra $120,000 in wealth. The compound growth on the extra contributions eventually dwarfs the contributions themselves.
Lever 3: Reduce Investment Fees
Fund expense ratios are quietly subtracted from your returns every year. Moving from a 1% expense ratio fund to a 0.03% index fund saves nearly 1% annually — which compounded over 30 years on $300,000 is approximately $165,000.
30-year impact of expense ratio on $500/month investment + $10,000 starting
| Fund Expense Ratio | Effective Return (7% gross) | Balance After 30yr ($500/mo, $10K start) | Lost to Fees vs. 0.03% |
|---|---|---|---|
| 0.03% (index fund) | 6.97% | $604,000 | — |
| 0.25% (ETF) | 6.75% | $578,000 | $26,000 |
| 0.50% (some mutual funds) | 6.50% | $551,000 | $53,000 |
| 1.00% (active fund) | 6.00% | $500,000 | $104,000 |
| 1.50% (some 401k options) | 5.50% | $453,000 | $151,000 |
A 1% expense ratio on a $200,000 investment costs $2,000/year directly. But compounded over 20 more years, that $2,000 not invested grows to $7,739. Fees steal both current returns and future compounding. Always check the expense ratio of every fund in your accounts.
Lever 4: Maximize Tax-Advantaged Accounts
A 7% return in a taxable account vs. a Roth IRA: after 30 years, the taxable account loses roughly 25–30% of gains to annual taxes on dividends and realized gains. The Roth account compounds the full 7% forever. On $500/month over 30 years, this difference can be $200,000+.
Lever 5: Automate Contribution Increases
Set your 401(k) contribution to auto-increase 1% per year. Starting at 6% contribution, by Year 10 you’re at 16% without any active decision. Most people don’t notice the 1% annual bump — but the compound impact is enormous.
See How Much Earlier You Can Hit Your Target
Enter your savings rate and try the 4 levers — see how much faster you reach $500K, $1M, or your custom goal.