Compound Interest Calculator

Free Compound Interest Calculator

See how your money grows with compound interest. Enter principal, interest rate, compounding frequency, time period, and optional monthly contributions.

Enter your starting principal amount, expected annual interest rate, and investment time frame in years. Choose how often interest compounds (daily, monthly, quarterly, or annually), as more frequent compounding yields higher returns. Optionally add regular monthly contributions to see how consistent investing accelerates growth. Tuttilo generates a year-by-year breakdown showing your balance growth, separating contributed principal from earned interest. A visual chart illustrates the exponential curve of compound growth. All calculations are performed locally in your browser for complete privacy of your financial planning.

College students model different savings strategies to understand how starting early with small monthly contributions outperforms larger contributions started later. Retirement planners project their nest egg growth by inputting current 401(k) balances with expected contribution rates. Parents saving for children's education calculate how much they need to set aside monthly to reach a specific goal in 18 years. Financial advisors demonstrate to clients the dramatic difference between 6% and 8% annual returns over 30-year periods.

The Rule of 72 offers a quick mental check: divide 72 by your interest rate to find how many years it takes to double your money. Tax-advantaged accounts like Roth IRAs maximize compound growth since you never pay taxes on the earnings. Starting 10 years earlier with compound interest often produces better results than doubling your contribution amount later. Don't underestimate how regular monthly additions amplify compound growth—a $200 monthly contribution can add more to your final balance than the original principal in long time horizons.

All processing happens directly in your browser. Your files never leave your device — no server uploads, no cloud storage, no data retention. The tool works offline once loaded, requires no registration, and is completely free with no usage limits.