Rule of 80 Calculator

Rule of 80 Calculator calculator can be used to estimate the age at which your investment's return on investment will decline to 80% of its initial value, based on a constant growth rate.

Input Parameters

Calculation Results

Calculation Formula

Age = ln(1.2) / ln(1 + (Return Rate / 100))

Where:
- Initial Investment: Your starting investment amount
- Annual Return Rate: The percentage return you expect annually
- Age: The age at which your investment return will be 80% of its initial value

Rule of 80 Calculator Calculator Usage Guide

Learn how to use the Rule of 80 Calculator calculator and its working principles

How to Use This Calculator

  1. Enter your initial investment amount in the first field.
  2. Enter your expected annual return rate (as a percentage) in the second field.
  3. Click the "Calculate" button to see the estimated age at which your investment return will decline to 80% of its initial value.
  4. Use the "Reset" button to clear all inputs and start over.

Understanding the Rule of 80

The Rule of 80 is a financial principle that estimates how long it will take for an investment to decline to 80% of its initial value at a constant growth rate. This rule is particularly useful for retirement planning and investment horizon assessment.

The formula used in this calculator is: Age = ln(1.2) / ln(1 + (Return Rate / 100))

Example

For example, if you invest $10,000 at an annual return rate of 7%, the calculator will show that your investment will be worth 80% of its initial value (or $8,000) approximately 14 years from now.

Important Considerations

Keep in mind that this is a simplified model and does not account for factors such as:

  • Compound interest frequency
  • Annual return rate fluctuations
  • Taxes and fees
  • Inflation

This calculator should be used as a rough estimate and not as definitive financial planning advice.