The Rule Of 72: How Long Money Takes To Double

Every number below is an invented example, and every claim is checked against a primary source - you can see the sources at the end.

The rule of seventy-two estimates when money doubles. Day to day, growth looks like equal, straight steps. But compound growth earns growth, so the line bends.

The rule: divide seventy-two by the rate. Invented six percent: seventy-two over six is twelve years. Invented nine percent: seventy-two over nine is eight years.

It is an estimate: close, but not exact. It says nothing about where to put money. Seventy-two over the rate. No calculator needed.

Sources

Each statement in the film was checked against its own source before it was made:

• The Rule of 72 estimates doubling time by dividing 72 by the rate - investor.gov
• The rule is an estimate, stated as approximate by the source itself - investor.gov
• The growth the rule estimates is compound growth - investor.gov

What this is not

This is an explanation of a money mechanic, not financial advice. There are no recommendations, no products, no predictions, and no promise about what any amount of money will do. The film shows the arithmetic of a rule that has been used for a long time; what you do with it is your own decision.

Watch it

This post accompanies the film: The Rule Of 72: How Long Money Takes To Double

Sources checked at time of publication. Educational content only - never financial advice.