Compound Interest Calculator
Estimate how your investment can grow over time with compound interest and regular contributions.
Enter Your Investment Details
Enter your starting investment, regular contributions, interest rate and investment period.
Your Results Will Appear Here
Enter your investment details to estimate future value and compound interest earnings.
How Compound Interest Works
Compound interest is calculated on the original investment and on interest accumulated over previous periods. Regular contributions can increase the amount invested and the potential growth over time.
Compound Interest Formula
Periodic Rate = (1 + Annual Rate ÷ Compounding Frequency)Compounding Frequency ÷ Contribution Frequency − 1
Number of Contributions = Investment Period × Contributions per Year
Future Value of Initial Investment = Initial Investment × (1 + Periodic Rate)Number of Contributions
Future Value of Contributions = Contribution × (((1 + Periodic Rate)Number of Contributions − 1) ÷ Periodic Rate)
Future Value = Future Value of Initial Investment + Future Value of Contributions
When the interest rate is 0%, the future value equals the initial investment plus all regular contributions.
Calculation Example
Suppose you invest $1,000 initially and contribute $100 monthly for one year, with a nominal annual interest rate of 12% compounded monthly.
- Initial investment: $1,000.
- Monthly contribution: $100.
- Annual interest rate: 12%.
- Compounding frequency: Monthly.
- Total contributions: $2,200.
- Estimated future value: approximately $2,395.08.
Frequently Asked Questions
What is compound interest?
Compound interest means earning interest on both your original investment and previously accumulated interest.
Can I calculate compound interest without regular contributions?
Yes. Set Regular Contribution to zero to calculate growth from your initial investment alone.
Can I calculate an investment with no initial deposit?
Yes. Set Initial Investment to zero and enter a regular contribution greater than zero.
When are regular contributions added?
This calculator assumes each regular contribution is made at the end of its contribution period. Contributions therefore do not earn interest for the period in which they are added.
What if the contribution frequency differs from the compounding frequency?
The calculator converts the nominal annual interest rate into an equivalent effective rate for each contribution period. This allows different contribution and compounding frequencies to be compared consistently.
Are taxes, fees and inflation included?
No. Results do not deduct taxes, investment fees or inflation. Actual returns may differ, and investment returns are not guaranteed.
Important: This calculator provides an estimate for educational and planning purposes only. It is not financial advice or a guarantee of investment returns.