How this Rule of 72 calculator works
The Rule of 72 is a quick mental shortcut for estimating how long it takes money to double.
Years to Double ≈ 72 ÷ Annual Return
When it is useful
- Comparing investment return assumptions quickly.
- Explaining compound growth in simple terms.
- Estimating inflation’s impact on purchasing power.
Important note
The Rule of 72 is an approximation. The exact result uses logarithms and can differ slightly at very low or very high rates.