Starting amount (present value).
Additional amount added each month.
Your Results
Enter your investment details and click calculate.
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What This Calculator Does
This compound interest calculator helps investors, savers, and financial planners project the future value of an investment or savings account. It supports daily, monthly, quarterly, semi-annual, and annual compounding frequencies. You can also include regular monthly contributions to see how consistent investing accelerates wealth accumulation over time. The tool generates a year-by-year growth table so you can visualize your progress at each milestone.
The Formula
P is the initial principal, r is the annual interest rate as a decimal, n is the number of compounding periods per year, t is the number of years, and PMT is the periodic contribution adjusted to the compounding frequency. The first term calculates the growth of the lump sum. The second term calculates the future value of a series of equal contributions. Together they give the total future value of the investment.
Step-by-Step Example
Enter your starting amount
This is the initial principal or present value. Example: $10,000 initial deposit.
Set monthly contributions
Enter the amount you plan to add each month. Example: $200 per month.
Choose rate and compounding
Enter 7% annual rate with monthly compounding. The calculator converts the annual rate to a periodic rate automatically.
Review the results
With $10,000 initial, $200/month, 7% compounded monthly for 10 years, the future value is approximately $44,677. Total contributions: $34,000. Total interest earned: $10,677.
Real-World Use Cases
Retirement Planning
Project how much your 401(k) or IRA will grow over 20 to 30 years with regular contributions and compound growth.
Savings Goal Tracking
Determine how long it will take to reach a savings target such as a down payment, emergency fund, or college fund.
Comparing Investment Options
Compare the impact of different compounding frequencies and interest rates to choose the best savings account or investment vehicle.
Common Mistakes to Avoid
Confusing nominal annual rate with effective annual rate. Compounding frequency changes the actual yield.
Forgetting to account for inflation. A 7% nominal return with 3% inflation yields roughly 4% real growth.
Ignoring fees and taxes that reduce the effective return on investments.
Assuming constant returns. Real investment returns fluctuate year to year.
Frequently Asked Questions
Accuracy and Disclaimer
This calculator provides estimates based on a fixed interest rate and regular contributions. Actual investment returns vary and are not guaranteed. Past performance does not predict future results. This is not financial advice. Consult a licensed financial advisor for personalized investment guidance.
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