Compound Interest Calculator — Daily, Monthly & Annual Growth
Compound interest is often called the eighth wonder of the world — and for good reason. When your investment earnings generate their own earnings, growth accelerates in a way that can turn modest, consistent investments into significant wealth over time.
This calculator lets you visualize exactly how your money grows. The stacked chart separates your total contributions from pure interest earnings, making it easy to see when your money starts working harder than you do.
Estimates only — not financial advice.
How to Use the Compound Interest Calculator
- 1
Enter your initial investment — the lump sum you’re starting with.
- 2
Set your monthly addition — the amount you plan to invest every month going forward. Even $100 per month can grow significantly over long periods.
- 3
Input your expected annual interest rate. For reference, the S&P 500 has historically returned about 10% annually before inflation (roughly 7% after).
- 4
Choose your investment period in years. The calculator will show you how much of your final balance comes from your own contributions versus the interest earned on those contributions — the difference can be eye-opening.
- 5
Experiment with the time horizon. An extra 10 years of compounding can more than double your eventual balance, even without increasing your monthly contribution.