Compound Interest Calculator
See exactly how your savings or investments grow over time — with a year-by-year breakdown and visual chart.
Year-by-Year Breakdown
| Year | Start Balance | Contributions | Interest | End Balance |
|---|
Ready to put this to work?
A high-yield savings account or a low-cost index fund are the most common vehicles for compound growth. The numbers above assume consistent returns — always check fees and tax implications for your situation.
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How Compound Interest Works
Compound interest means you earn interest on your interest, not just your original principal. Over long timeframes, this creates exponential growth — what Albert Einstein supposedly called "the eighth wonder of the world."
The classic formula for a lump-sum investment is:
When you add regular contributions, the future value of each contribution compounds separately. This calculator sums them precisely each period.
Compounding Frequency Matters Less Than You Think
The difference between monthly and daily compounding on a 7% rate over 20 years is less than 0.07% of the final value. Choosing the right investment vehicle and contributing consistently has orders of magnitude more impact than compounding frequency.
What matters most: starting early, contributing regularly, minimizing fees, and staying invested.