Compound Interest Calculator
Estimate how your money can grow with compounding — including optional monthly contributions. Clear, global, and easy to use.
Why compound interest matters
Compound interest is the engine behind long-term investment growth: you earn interest not only on your initial amount, but also on the interest that has already been added. Over time, that compounding effect can outweigh small differences in rates and even make modest monthly contributions add up to a meaningful balance. Use a compound interest calculator to compare scenarios—change the rate, contribution amount, and compounding frequency—and focus on what moves the needle most: time in the market, consistent saving, and keeping fees low. The goal isn’t a perfect forecast; it’s a clear baseline you can use to plan and understand how growth accelerates when returns start earning returns.
Compound calculator
The core tool for estimating growth over time.
Open calculator Principal + rate + years + compounding frequency.Best guide to start
Understand compounding in 3 minutes.
How compound interest works What compounding is and why time matters most. What is compound interest? The definition, formula, and a quick example. Compound interest formula explained Break down the formula with step-by-step examples. Compound vs simple interest A side-by-side comparison with a quick table and example. Compounding frequency explained Daily vs monthly vs yearly — and how big the difference is.