Compound Interest Calculator
See how your money grows over time with compound interest. Adjust contributions, rates, and time horizons to compare different investment strategies and plan your financial future.
What is compound interest?
Compound interest is interest earned on your initial investment plus the interest that accumulates. Think of it as a snowball rolling downhill — it starts small, but as it rolls, it picks up more snow (interest), getting bigger and moving faster. Albert Einstein reportedly called it the "eighth wonder of the world" because money growing on itself accelerates over time.
How it works: In year 1 at 7% return, $10,000 earns $700 in interest. In year 2, you earn 7% on $10,700 — that's $749. By year 30, a single year's growth exceeds your original investment. The tool below lets you visualize this effect.
Compound Interest Calculator — Project Your Investment Growth for Free
Free compound interest calculator. Project your investment growth with customizable contributions, rates, and time horizons. Save scenarios and export CSV.