Compound Interest Calculator
Calculate how your money could grow over time with compound interest, regular contributions, and an estimated annual rate of return.
Calculate Compound Interest
Enter your starting investment, regular contributions, interest rate, investment period, and compounding frequency to estimate your future balance.
Starting Investment
Regular Contributions
Interest & Growth
Investment Period
Inflation Adjustment
Compound Interest Result
Estimated future value of your investment, including regular contributions.
| Initial Investment | — |
| Regular Contribution | — |
| Contribution Frequency | — |
| Annual Interest Rate | — |
| Compounding Frequency | — |
| Investment Period | — |
| Total Contributions | — |
| Total Interest Earned | — |
| Inflation-Adjusted Value | — |
Step-by-Step Calculation
What Is Compound Interest?
Compound interest is interest earned on both the original amount of money and previously accumulated interest. Over longer periods, compounding can have a significant effect on the growth of savings and investments.
Compound Interest Formula
For a single initial investment without additional contributions, the standard compound interest formula is:
A = future value
P = initial principal
r = annual interest rate as a decimal
n = number of compounding periods per year
t = time in years
When regular contributions are added, the future value of those contributions is calculated separately and combined with the growth of the initial investment.
Why Compounding Frequency Matters
Interest can be compounded daily, weekly, monthly, quarterly, semiannually, or annually. When other assumptions remain the same, more frequent compounding generally results in a slightly higher effective return.
Why Regular Contributions Matter
Adding money regularly can substantially increase the amount accumulated over time. Each contribution gets an opportunity to earn returns for the remaining investment period.
Compound Interest Example
Suppose you invest 10,000 initially and earn an average annual return of 7% for 20 years, while also adding 500 each month. The calculator combines the initial investment and regular contributions to estimate the potential future value.
The actual outcome can differ because investment returns are not guaranteed and may vary from year to year.
Inflation and Purchasing Power
A future balance may have less purchasing power than the same amount today because prices can increase over time. The inflation adjustment provides an estimate of what the projected balance could be worth in today’s money.
Related Calculators
Important: This calculator is provided for general informational and educational purposes only and does not constitute financial, tax, legal, investment, or other professional advice. Results are estimates based on assumptions entered by the user and are not a guarantee of future investment performance. Actual interest rates, returns, fees, taxes, contributions, inflation, and market conditions may differ substantially. Consider your individual circumstances and consult a qualified professional when appropriate before making important financial decisions.