The ideas behind the numbers
Every what-if on this site rests on a handful of simple ideas. Understand these four and you'll read any return — here or anywhere — with clear eyes.
Dollar-cost averaging, explained (with the math)
Why buying a little at a time can beat trying to pick the perfect moment — and when it doesn't.
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CAGR: the growth number that doesn't lie
Why the compound annual growth rate is the only honest way to say 'how much per year' — and how a simple average fools you.
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Nominal vs. real returns: what inflation quietly takes
Your investment can grow on paper while buying you less. Here's how to see the difference — and why we always show 'today's dollars'.
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Maximum drawdown: would you actually have held?
The biggest peak-to-trough fall an investment put you through — and why it predicts behavior better than any return number.
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Want the site-specific version — exactly where our data comes from and the precise formulas behind every figure? That lives on the methodology page.