How accurate is the Rule of 72?

The Rule of 72 is remarkably accurate for interest rates between 6% and 14%. For higher rates (15% to 25%), the Rule of 73 or 74 offers slightly closer mathematical precision.

Rule of 72 Calculator

Investment Details

Expected Annual Rate of Return

Time to Double

Approximate Years to Double

Guide & Methodology

About the Rule of 72 Calculator

Estimate how many years it will take to double your investment or money at a given fixed rate of return.

What this calculator does

Calculates doubling time for any interest rate or CAGR.
Helps compare growth rates of various asset classes (fixed deposits vs equity).
Calculates required rate of return to double wealth within a target number of years.

How it Works & Key Inputs

Step 1

Enter Rate of Return

Input expected annual compound return percentage.

Step 2

Instant Doubling Timeline

View the approximate number of years required to double your capital.

Core Calculation Parameters

Interest / Return Rate (%)Expected annual compounding rate.

Formula & Calculation Logic

Mathematical Model

Years to Double ≈ 72 / Annual Interest Rate (%) | Exact Years = ln(2) / ln(1 + r)

Exponential compounding doubling approximation.

Variables Breakdown

YearsTime required for investment value to reach 2× initial capital

Calculation Example: At 12% annual return, an investment doubles in approximately 72 / 12 = 6 years.

Frequently Asked Questions (FAQ)

Disclaimer: This calculator is provided for educational and illustrative purposes only. Actual financial outcomes may vary based on statutory changes, lender terms, fund fees, and prevailing market dynamics.