How long until your money doubles?
Stop thinking in percentages. Start thinking in doublings — it changes how you see every number. Type a rate and see how many years each doubling takes.
| Yearly rate | Rule of 72 | Exact years to double |
|---|
The Rule of 72: divide 72 by the yearly rate to get roughly how many years it takes to double. At 8%, 72 ÷ 8 = 9 years. It's a shortcut — the calculator also shows the exact answer. It works the other way too: at 3% inflation, prices double in about 24 years.
Why such a simple trick matters
It turns a percentage into something you can feel. "8% a year" sounds small. "Doubles about every 9 years" doesn't. And it shows how big the gap between two rates really is over time: at 4%, money doubles every 18 years; at 8%, every 9 — twice as many doublings in the same time. Watch the full year-by-year version in the compound interest calculator.
The same math works against you. A loss has to be earned back on a smaller pile, which is why traders guard against big drops first. See how much a loss takes to recover.
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