Guide
See how your money grows with compound interest and regular monthly deposits. Enter your starting balance, contribution amount, interest rate, and time horizon to project future value and total interest earned.
Why Compound Interest Matters
Compound interest means you earn returns on your returns, not just your original principal. Over decades, this snowball effect turns modest monthly savings into substantial wealth — Albert Einstein reportedly called it the eighth wonder of the world.
The three variables you control are how much you invest, how long you stay invested, and your average return. Time is the most powerful of the three for long-term goals.
Monthly Contributions vs Lump Sum
Dollar-cost averaging through monthly deposits smooths market volatility and builds the habit of consistent investing. Lump-sum investing can outperform if markets rise, but monthly contributions are easier for most people and still produce excellent long-term results.
Even $200/month at 7% over 30 years grows to over $240,000 — with $168,000 of that coming from compound growth alone.
Key Takeaways
- Compound growth accelerates dramatically in later years.
- Consistent monthly investing beats trying to time the market.
- Higher rates and longer timelines multiply results exponentially.
- Reinvest dividends and interest to maximize compounding.