Compound Interest Calculator
See how your money grows over time with the power of compound interest.
Enter your investment details and click Calculate.
Growth Over Time
Year-by-Year Breakdown
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About Compound Interest
What is Compound Interest?
Compound interest is interest calculated on both the initial principal and the accumulated interest from previous periods. It makes your money grow exponentially over time.
The Rule of 72
Divide 72 by your annual interest rate to estimate how many years it takes to double your money. For example, at 7% interest, your money doubles in about 10.3 years.
Start Early
Time is the most powerful factor in compound interest. Starting 10 years earlier can more than double your final balance, even with the same contributions.
Common Use Cases
Estimate how much your savings will grow by retirement based on current contributions and expected returns.
Calculate how much to save monthly to reach a target amount for tuition fees by a specific year.
See how quickly an emergency fund grows in a high-yield savings account with regular deposits.
Compare different interest rates and compounding frequencies to find the best option for your money.
Understand how compound interest works against you on loans and credit card debt.
Visualize the power of compound interest with interactive charts for classroom or self-study.
Frequently Asked Questions
What is the difference between simple and compound interest?
Simple interest is calculated only on the initial principal. Compound interest is calculated on the principal plus all previously accumulated interest, causing your balance to grow exponentially over time.
How does compounding frequency affect my returns?
More frequent compounding (daily vs. annually) produces slightly higher returns because interest is added to the balance more often, allowing it to earn interest sooner. The difference is usually small for typical savings rates.
Does this calculator account for taxes or inflation?
No. This calculator shows nominal growth before taxes and inflation. Actual purchasing power may differ. For a more realistic estimate, subtract your expected tax rate from the interest rate, or use a real (inflation-adjusted) rate.
What interest rate should I use?
It depends on the investment. Savings accounts typically offer 0.5–5%, bonds 3–6%, and broad stock market index funds have historically averaged around 7–10% annually before inflation. Use a conservative estimate for planning.
Are my financial details sent to a server?
No. All calculations happen entirely in your browser. Your investment amounts and settings are never transmitted to any server.
Should I rely on this calculator for financial decisions?
This tool provides estimates for educational and planning purposes. Actual investment returns vary and are not guaranteed. For important financial decisions, consult a qualified financial advisor.