Why Compound Interest Feels Like a Trick

Compound interest is one of the few places in finance where the math is genuinely simple and the intuition is genuinely wrong. Most people, asked to guess how much $10,000 grows to at 7% over 30 years, guess low — often by half or more. Linear thinking is the default; compounding is exponential, and our instincts aren't built for exponential curves.

That's the actual reason the Compound Interest Calculatorshows a year-by-year table instead of just a final number. A single answer ("$76,123") doesn't correct the intuition. Watching the curve bend upward — slow at first, then visibly steeper in the later years — does.

There's a second reason we built it this way: the same curve works in reverse as a warning. Credit card debt compounds too. The tool doesn't moralize about that, but showing the mechanism plainly does more work than a warning label would.

None of this needed to be complicated. It needed to stop hiding the shape of the curve behind a single output field.