Finance Calculator

Compound Interest Calculator

Calculate future investment value with initial investment, monthly contribution, annual interest rate, and investment duration.

📝Inputs

📊Results

Enter your values and click Calculate to see results.

Learn About Compound Interest

What is this calculator?

This compound interest calculator estimates how your money grows over time when interest is reinvested and you optionally add monthly contributions. It is ideal for retirement planning, savings goals, and comparing investment scenarios.

How does it work?

Enter your starting balance, monthly deposit, expected annual return, time horizon, and compounding frequency. The calculator simulates periodic compounding and contributions to project your ending balance, total deposits, and interest earned.

Formula

$$A = P(1 + \frac{r}{n})^{nt} + PMT \times \frac{(1 + \frac{r}{n})^{nt} - 1}{\frac{r}{n}}$$

Where $A$ is future value, $P$ is principal, $PMT$ is periodic contribution, $r$ is annual rate, $n$ is compounding periods per year, and $t$ is years.

When should you use it?

  • Planning long-term savings or retirement contributions
  • Comparing different contribution amounts or time horizons
  • Understanding the impact of compounding frequency on returns

Example

Invest $10,000 initially, add $500/month for 20 years at 7% compounded monthly. Your future value would be approximately $287,000+, with over $130,000 in interest earned.

Frequently Asked Questions