Rule of 72 calculator

Rule of 72: when does your money double?

Your money doubles in 10.3 years (rule of 72)

Exact calculation: 10.2 years
Triple (rule of 114): 16.3 years

The rule of 72 is a mental shortcut: dividing 72 by the annual return gives you, roughly, the years an investment takes to double through compound interest. Not financial advice.

This rule of 72 calculator works out how many years it takes your money to double at a given annual return, alongside the exact calculation.

The power of doubling

The rule of 72 is one of the handiest mental tools for understanding compound interest: the higher the return, the sooner your money doubles. At 7% a year, it doubles roughly every ten years — and each following doubling starts from a bigger base.

For guidance only — this is not financial advice.

FAQ

What is the rule of 72?

A mental shortcut to estimate how many years it takes an investment to double: divide 72 by the annual return. At 6%, about 12 years; at 9%, about 8.

Is it accurate?

It's a very good approximation for typical rates (between 4% and 12%). For the precise figure, this tool also shows the exact logarithmic calculation.

What about the rule of 114?

Same idea, but for tripling your investment: divide 114 by the annual return.