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Rule of 72 Calculator

Verified formula Updated Jun 2026 Private — runs on your device

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Verified formula Private

Years to double (Rule of 72)

9.0

Years to double (Rule of 70)
8.8
Years to triple (Rule of 114)
14.3

For general information only — not financial, tax, legal or medical advice. Verify before you rely on it.

How to use the Rule of 72 Calculator

The Rule of 72 Calculator works out your years to double (rule of 72), along with 2 related figures in an instant. Enter annual return rate and the result updates as you type — it is free, needs no sign-up, and runs entirely in your browser so your figures stay private.

  1. Enter the annual return rate.
  2. Read off your years to double (rule of 72), together with years to double (rule of 70) and years to triple (rule of 114) — the calculator updates automatically, with no button to press.

Formula

The Rule of 72 Calculator uses the formula:

Years to double (Rule of 72) = 72 ÷ Annual return rate

Worked example

For example, with annual return rate of 8%, the years to double (rule of 72) is 9.0.

Inputs used
Annual return rate 8%
Results
Years to double (Rule of 72) 9.0
Years to double (Rule of 70) 8.8
Years to triple (Rule of 114) 14.3

Results are estimates for educational use, not professional advice.

Frequently asked questions

It is a quick way to estimate how long an investment takes to double: divide 72 by the annual return rate. At 8% a year, money doubles in about 9 years.

It is a close approximation for rates between about 6% and 10%. For lower rates the Rule of 70 is slightly more accurate, which is why it is shown too.

Dividing 114 by the return rate estimates how long money takes to triple. At 8% that is about 14.25 years.

No. It uses the nominal return only. To estimate doubling in real terms, use your return after inflation.

The Rule of 72 Calculator uses the formula: Years to double (Rule of 72) = 72 ÷ Annual return rate. For example, with annual return rate of 8%, the years to double (rule of 72) is 9.0.

Enter the annual return rate. Read off your years to double (rule of 72), together with years to double (rule of 70) and years to triple (rule of 114) — the calculator updates automatically, with no button to press.

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