Rule of 72 Calculator
Estimate how long it will take to double your investments, or calculate the interest rate required to hit your doubling goals.
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Compounding Return Rate
Expected annual compounding rate of return.
Inflation Power Eroder
Purchasing Power Halves In
22.76 Years
At 3% inflation, your cash loses half its purchasing power in exactly 22.76 years (Rule of 72 estimates 24.0 years).
Doubling Time (Rule of 72)
9.00 Years
Estimated shorthand calculation (72 / rate).
Exact Doubling Time
9.01 Years
Exact compounding math using logarithms/exponential fractions.
Estimate vs Exact Compounding
At a 8% return, the Rule of 72 estimate is off by 0.01 years (0.1%) compared to the exact compounding formula.
Sensitivity: Rule of 72 vs. Exact Doubling Time
* Observe how the Rule of 72 (orange) overestimates doubling times at very low rates and underestimates doubling times at higher returns compared to exact compound formulas (green).
Rule of 114 (Tripling Time)
How long it takes to triple your money (3x).
Rule of 144 (Quadrupling Time)
How long it takes to quadruple your money (4x).
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