- Enter Details — Initial investment, annual rate, years, compounding frequency, monthly contribution.
- Calculate — Click 'Calculate' to see final balance, total interest, and total deposits.
- View Chart — Visual bar chart showing growth over time.
- Download — Export year-by-year breakdown as CSV.
Compound Interest Calculator — Visualize Investment Growth
The Compound Interest Calculator is a free tool that shows how your money grows over time with compound interest and regular contributions. It features a visual chart, year-by-year breakdown table, and CSV export — all running entirely in your browser.
What is Compound Interest?
Compound interest is often called the "eighth wonder of the world." Unlike simple interest, which only earns on your original principal, compound interest earns interest on your accumulated interest. This creates exponential growth over time.
For example, $10,000 invested at 7% annually for 30 years grows to $76,123 with compound interest — but only $31,000 with simple interest. That's the power of compounding.
The Compound Interest Formula
A = P(1 + r/n)^(nt)
- A = Final amount
- P = Principal (initial investment)
- r = Annual interest rate (decimal)
- n = Compounding frequency per year
- t = Time in years
Features
- Monthly Contributions — Model regular investment strategies.
- 5 Frequencies — Daily, monthly, quarterly, semi-annual, annual.
- Visual Chart — Bar chart showing deposits vs interest growth.
- Year-by-Year Table — Detailed breakdown of balance and interest per year.
- CSV Export — Download the full breakdown as a spreadsheet file.
Investment Strategies
- Start Early — Time is the most important factor in compound interest.
- Contribute Regularly — Even small monthly contributions have huge long-term impact.
- Reinvest Dividends — Keep your money compounding.
- Increase Rate — Even 1% higher returns compound significantly over decades.
Privacy
All calculations run in your browser. No financial data is transmitted.