Project investment growth with full year-by-year tables. The most powerful tool for long-term wealth planning — used by serious investors worldwide.
| Year | Balance | Total Invested | Interest Earned | Annual Gain |
|---|
Compound interest is interest earned on both the initial principal and all previously accumulated interest. Unlike simple interest, it creates an exponential growth curve — the longer you stay invested, the faster your money accelerates.
Formula: A = P(1 + r/n)^(nt) — where P = principal, r = annual rate (decimal), n = compounding frequency per year, t = years. Monthly contributions stack on top, each compounding from the moment deposited.
Starting 10 years earlier typically doubles your final balance. A 25-year-old investing $10k beats a 35-year-old investing $20k — time is the most powerful variable.
12× per year is standard for most accounts. Daily (365×) offers marginal improvement — the compounding frequency matters far less than the rate and time.
Historical average ~10% annually before inflation, ~7% real. Use 6–8% for conservative long-term projections in your planning.
401(k), IRA, Roth IRA — compounding without annual tax drag. Maximizing these before taxable accounts significantly boosts long-term returns.
Invest $10,000 at 7% annually for 30 years with $200/month contributions. You deposit $82,000 total. Your ending balance: over $242,000. That’s $160,000 generated purely by compounding — 66% of the final value came from interest, not contributions.
Start as early as possible — every decade of delay roughly halves your final balance. Automate monthly contributions so you never miss a deposit. Reinvest all dividends. Minimize fees — a 1% annual fee silently destroys ~25% of your 30-year returns. Prioritize tax-advantaged accounts.
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