Compound Interest Calculator

How to Use Enter the principal amount, annual interest rate, and investment duration in years. Select the compounding frequency (annually, semi-annually, quarterly, monthly, or daily). Add a regular contribution amount if applicable. Review the final balance, total interest earned, and a year-by-year growth chart. Who Is This For Savers and investors building a long-term financial plan, anyone who wants to see how much a rate difference compounds over time, and people planning for retirement or a major financial goal. Key Features • Simple vs. compound interest comparison • Compounding frequency selection • Regular contribution support • Year-by-year asset growth chart • Inflation-adjusted real value option Frequently Asked Questions Q: How much more does compounding earn vs. simple interest? A: On $10,000 at 5% for 30 years: simple interest = $25,000, compound interest ≈ $43,219. That is $18,219 more from compounding alone. Q: What is the Rule of 72? A: Divide 72 by the annual interest rate to estimate when money doubles. At 6% interest, money doubles in about 12 years (72 ÷ 6 = 12). Q: Can it account for taxes on interest? A: Enable the 'After-tax return' option to deduct tax from interest at your specified rate and see the true net growth. Tips A seemingly small 1–2% difference in return rate becomes enormous over 30 years. Use this tool to compare investment options with different rates. Tax-advantaged accounts (IRA, 401k equivalents) preserve the full compound effect by deferring taxes.