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Money Doubling Time Calculator

How long until an investment doubles, exactly and by the Rule of 72.

Enter your values

ⓘ Live results

Results
Years to double
9.01 years
Rule of 72 estimate
9 years
Years to triple
14.27 years
Effective annual rate
8%
Value after doubling
$20,000.00
Value in 10 years
$21,589.25

Quick answer

Exact doubling time is ln(2) ÷ ln(1 + r). The Rule of 72 approximation, 72 ÷ rate, is within a few months for rates between 4% and 12%.

Years = ln(2) ÷ ln(1 + r)

How to use the Money Doubling Time Calculator

  1. 1Enter the annual return you expect.
  2. 2Pick how often returns compound.
  3. 3Read the exact doubling time and compare it with the Rule of 72 shortcut.

Worked example

Using the values the calculator loads with:

Inputs

  • Annual return8 %
  • Starting amount10000 $
  • CompoundingYearly

Results

  • Years to double9.01 years
  • Rule of 72 estimate9 years
  • Years to triple14.27 years
  • Effective annual rate8%
  • Value after doubling$20,000.00
  • Value in 10 years$21,589.25

Frequently asked questions

Is the Rule of 72 accurate?

Very close between 4% and 12%. At 2% use 70, at 20% use 76 — the ideal numerator drifts upward as the rate rises.

Should I use nominal or real returns?

Use a real (after-inflation) return if you want to know when your purchasing power doubles rather than the headline balance.

About this calculator

Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.