Beta of a Security or Portfolio Calculator

Enter value and click on calculate. Result will be displayed.

b = (R - Rf) / (Rm - Rf)
R = Expected Rate of Return
Rf = Risk Free Interest Rate
Rm = Expected Market Return
b = Stock Beta

Expected Rate of Return (R):
%
Risk Free Interest Rate (Rf):
%
Expected Market Return (Rm):
%
Stock Beta (b):

A Beta of a Security or Portfolio Calculator is a tool that helps you calculate the Beta (a measure of volatility or market risk) of a particular security or a portfolio of securities. The Beta value shows the relationship between the security or portfolio's returns and the returns of the market (usually represented by a market index like the S&P 500).

Steps to calculate Beta of a security or portfolio:
​

Where:

Covariance: A measure of how the security returns move with the market returns.
Variance: A measure of the volatility of the market returns.
To use this formula, you will need historical return data for both the security and the market. The calculator will help compute these values automatically based on this data.

2. Beta of a Portfolio:
Formula:

Where:

Weight of Asset i: The proportion of the total portfolio value invested in the i-th asset.
Beta of Asset i: The Beta of each individual security in the portfolio.
This formula allows you to calculate the overall Beta of a portfolio by averaging the Betas of the individual assets, weighted by their percentage of the total portfolio value.

Example:
If you have a portfolio with two stocks:
Stock 1 has a Beta of 1.2 and makes up 60% of the portfolio.
Stock 2 has a Beta of 0.8 and makes up 40% of the portfolio.
The Beta of the portfolio will be:

This means the portfolio is expected to be slightly more volatile than the market (since Beta > 1).

Where to Find a Beta Calculator:
Many financial websites and software like Yahoo Finance, Bloomberg, or online brokerage platforms offer Beta calculators. You simply need to enter the necessary data (such as historical returns, weights of securities in a portfolio, etc.), and the calculator will do the math for you.

Alternatively, you can build a custom calculator using a spreadsheet program like Excel by entering the necessary data and applying the formulas above.