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Tool

Compound interest

Choose what you could put away every month, a rate and how many years. The dotted line is your money alone; the green one is the same money earning on itself.

You would end up with

$589,020

Of that, $240,000 you put in and $349,020 is interest.

$1,000
8%
20

Just your contributions With compound interest

After 20 years: $589,020 — of which only $240,000 came from you.

An educational example with a constant rate, compounded monthly — real returns vary year to year.

What you learn here

  • Time does more work than the amount. The same contribution started ten years earlier ends up far ahead of a bigger one started late.
  • The first years look flat, and almost all of the growth there is your own deposits. The interesting part starts when the interest is bigger than what you put in.
  • A constant rate is a teaching device, not a promise: real returns move every single year, and the curve is never this smooth.
Read the full lesson: Simple vs. compound interest →

Educational tool. It assumes constant rates and ignores taxes, fees and any surprise; real returns and real inflation change every year. It is here to show the shape of the idea, not to plan your money with it, and it is not financial advice.