Compound Interest Calculator

1. Enter your initial investment amount (the starting principal).
2. Enter a monthly contribution amount (or leave at 0 for lump-sum only).
3. Set the annual interest rate as a percentage.
4. Choose the number of years for the investment period.
5. Select the compounding frequency (monthly, quarterly, or annually).
6. View the final balance, total contributions, interest earned, and year-by-year breakdown.

Understanding Compound Interest

Compound interest is one of the most powerful concepts in finance. Albert Einstein reportedly called it the "eighth wonder of the world." This calculator uses the standard compound interest formula: A = P(1 + r/n)^(nt) for the principal, plus the future value of an annuity formula for regular contributions. Together, these formulas show how your initial investment and ongoing deposits grow over time, accounting for interest that compounds at your chosen frequency.