Compound Interest Calculator
Free Compound Interest Calculator
See how your money grows over time with our free compound interest calculator. Enter your initial investment, interest rate, time horizon, and optional monthly contributions to instantly see your projected final balance, total interest earned, and a visual growth chart. This tool supports multiple compounding frequencies from annual to daily.
How to Use
Fill in the principal amount, annual interest rate, number of years, and compounding frequency. Optionally add a monthly contribution to see the impact of regular investing. Click "Calculate" to view the results and a bar chart showing year-by-year growth of your investment.
FAQ
What is compound interest?
Compound interest is interest calculated on the initial principal and also on the accumulated interest from previous periods. It causes your money to grow faster than simple interest, which is calculated only on the principal.
What formula does this calculator use?
The base formula is A = P(1 + r/n)^(nt), where P is the principal, r is the annual rate, n is the compounding frequency, and t is the time in years. Monthly contributions are compounded separately and added to the total.
How does compounding frequency affect returns?
More frequent compounding (e.g., daily vs. annual) results in slightly higher returns because interest is reinvested more often. The difference is more significant at higher interest rates and longer time periods.
Does this account for taxes or inflation?
No. This calculator shows nominal growth before taxes and inflation. Your real (inflation-adjusted) returns will be lower. Consult a financial advisor for tax-specific planning.
What is the Rule of 72?
The Rule of 72 is a quick way to estimate how long it takes to double your money. Divide 72 by the annual interest rate to get the approximate number of years. For example, at 8% interest, your money doubles in about 9 years.