Rule of 72
Quick definition: The Rule of 72 is a shortcut for estimating how many years it takes an investment to double: divide 72 by the annual rate of return.
In plain English
Years to double ≈ 72 ÷ annual return (%)
Example
At 8% a year, money doubles in about 72 ÷ 8 = 9 years. At 4% it takes about 18 years.
Why it matters
It is a quick mental tool for seeing how much difference a few percentage points make over time. It also works for inflation: at 3% inflation, prices double in about 24 years.
Limits
It is an approximation and works best for rates between about 6% and 10%. For exact figures, use a calculator.
Common mistakes
- Using it for very high or very low rates.
- Forgetting that real returns are not steady.
Investment Disclaimer
All information and tools on this website are provided for informational
purposes only. The calculations, examples, and projections are simplified
estimates and may not reflect real-world investment results.
Nothing on this website should be interpreted as financial, investment,
tax, or legal advice. You are solely responsible for your investment
decisions and any outcomes resulting from them.
Past performance and projected returns do not guarantee future results.
Always conduct your own research and consult a qualified financial advisor
before making investment decisions.