Compound Interest & Investment Calculator
Forecast your long-term wealth accumulation by calculating compound interest returns with recurring monthly contributions and visual yearly growth charts.
$207,242
$100,000
+$107,242
Compound Wealth Accumulation Over Time
Green represents compound interest gains; blue represents your out-of-pocket deposits.
The Power of Compounding Interest
Albert Einstein famously called compound interest the "eighth wonder of the world." Over long investment horizons (10 to 30 years), the interest generated on your previous gains drastically outpaces your original principal contributions.
Use this calculator to model index fund investments (e.g. S&P 500 averaging 8–10% annually), 401(k) / IRA contributions, or high-yield savings accounts.
How to Use Compound Interest & Investment Calculator (Step-by-Step)
Enter your initial principal, annual interest rate (%), and investment horizon in years.
Optionally add regular monthly contributions and choose compounding frequency.
Inspect the total future value, total interest earned, and interactive visual growth breakdown.
Applications
Common Use Cases
- Forecast long-term stock market, index fund, or retirement portfolio growth.
- Compare how different compounding frequencies (annual vs monthly vs daily) impact total wealth.
- Understand the power of compound interest vs pure deposits over 5 to 40 year horizons.
Privacy Guarantee
Zero Server Uploads
Unlike traditional online converters that upload your confidential documents to external cloud servers, MultiToolX executes computations in your browser runtime via HTML5 Canvas, Web Crypto, and WebAssembly.
Your data never leaves your device and cannot be viewed, stored, or harvested by anyone.
Compound Interest Formula & Wealth Growth: How Compounding Works
A comprehensive guide to compound interest calculations with annual, quarterly, and monthly compounding examples. Interactive formulas and wealth growth tips.
FAQ
Frequently Asked Questions
What is the compound interest formula used?
For regular contributions, it computes A = P(1 + r/n)^(nt) + PMT * [((1 + r/n)^(nt) - 1) / (r/n)], accounting for periodic deposits.