How accurate is the Rule of 72?

Very accurate between 6-10%. At 8%, exact doubling takes 9.006 years; Rule of 72 gives 9. Error increases outside this range.

Can it work for debt doubling?

Yes. A credit card at 24% APR will double the balance owed in 72/24 = 3 years if no payments are made.

What is the Rule of 114?

Rule of 114 estimates tripling time: Years approximately 114 / rate%. Rule of 144 estimates quadrupling time.

Rule of 72 Calculator

Estimate years to double an investment: Years approximately 72 / annual rate%. Quick mental math for comparing growth rates and understanding doubling time.

Principal ($)

Annual Rate (%)

Years

Compounding / Year

$ Finance Disclaimer: These calculators are for educational and illustrative purposes only. Results do not constitute financial advice. Consult a licensed financial advisor before making investment or borrowing decisions.

How to Use

Enter the values for the scenario you are assessing. Estimate years to double an investment: Years approximately 72 / annual rate%. Quick mental math for comparing growth rates and understanding doubling time. Use the rule of 72 result to inform your calculation.

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Frequently Asked Questions

How accurate is the Rule of 72?

Can it work for debt doubling?

What is the Rule of 114?