Compound Interest Calculator
Calculate how your investment grows over time with compound interest. See the power of compounding with our free online calculator — enter your principal, interest rate, and time period to get instant results.
How to Use the Compound Interest Calculator
To use our compound interest calculator, enter your starting principal (the amount you're investing today), your expected annual interest rate, the number of years you'll invest, and how frequently interest compounds. Then click "Calculate" to see your projected final balance.
The compound interest formula is: A = P × (1 + r/n)n×t, where P is principal, r is the annual rate as a decimal, n is compounding periods per year, and t is time in years.
Example Calculations
- Conservative investor: $5,000 at 4% for 20 years = $10,956 (+118%)
- Balanced portfolio: $10,000 at 7% for 15 years = $27,590 (+175%)
- Aggressive growth: $20,000 at 10% for 30 years = $348,988 (+1,644%)
The key takeaway: starting early makes an enormous difference. An investor who starts at 25 versus one who starts at 35 can accumulate double the wealth by retirement, even if they invest identical amounts.
Frequently Asked Questions — Compound Interest
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About This Calculator & Financial Disclaimer
This tool was built to help users mathematically project their financial goals using standard formulas. The default variables provided are for educational purposes only and do not represent guaranteed future market performance.
Not Financial Advice: We are not certified financial planners (CFP) or investment advisors. The stock market involves risk, and inflation can vary drastically. Please consult a licensed professional before making major financial decisions, executing a 72(t) early withdrawal, or rebalancing your portfolio.