Investment growth tool
Compound Interest Calculator
Project how an investment balance and monthly contributions may grow over time with annual compound interest. Use this investment growth calculator to compare long-term returns, contribution habits, and the power of compounding without complicated finance language.
Growth projection
Contributions vs. compounded value
See how your own deposits compare with the projected account value as compounding builds over time.
Annual compound interest calculator with monthly contributions
A compound interest calculator helps you estimate how investments can grow when earnings are reinvested. Instead of earning growth only on your starting amount, compound growth can earn returns on both your original money and the investment gains already added to the account.
How this compound interest calculator works
This calculator starts with your current investment balance, adds your monthly contribution, and compounds investment growth annually to estimate future value. The result separates total contributions from compound growth so you can see how much comes from your own deposits and how much comes from estimated investment returns.
Why monthly contributions matter
Regular monthly contributions can make a long-term investment plan more realistic and more powerful. Even small recurring deposits can grow over time when they are paired with compound interest. Try changing the monthly contribution, annual interest rate, or years to grow to compare different retirement, brokerage account, portfolio growth, or investment goal scenarios.
Compare compound interest over time
The chart above compares total contributions with compounded value year by year. This makes it easier to understand the difference between money you put in and projected interest earned. A longer time horizon often gives compounding more room to work, which is why this calculator is helpful for planning early and reviewing investment goals regularly.
Estimate only
This free compound interest calculator is for planning and education. Actual investment returns, taxes, fees, inflation, market performance, and account rules can change your real results. Use the estimate as a simple starting point, not a guarantee.