A beta of 1 means the stock tends to move with the market; 1.5 means 50% more volatile; below 1 less volatile; negative means it tends to move the opposite way. Use at least 20–60 periods (weekly or monthly prices) for a reliable estimate. Everything is calculated in your browser, so nothing you type is sent to our server.
How to use the Stock Beta Calculator
- Stock prices (oldest first)
- Benchmark prices (same dates)
Everything runs in your browser, so results appear instantly and nothing you type is sent to a server.
How it works
Paste the stock’s prices and the benchmark’s prices for the same dates, oldest first.
Tips
- Take figures from the same financial statements and the same fiscal year.
- Compare ratios with companies in the same industry, not across industries.
- Use several valuation measures together; no single ratio tells the whole story.
- Market prices change every second – refresh the share price before you rely on a result.
Common mistakes to avoid
- Mixing per-share figures with company totals.
- Using trailing earnings for one company and forward earnings for another.
- Forgetting dilution from options and convertible securities.
Formula
Returns: rₜ = Pₜ ÷ Pₜ₋₁ − 1 for the stock and the benchmarkBeta = covariance(stock, benchmark) ÷ variance(benchmark)R² = correlation²Worked example
Inputs — Stock prices (oldest first): 52, 53.1, 51.8, 54.6, 55.2, 54.1, 56.8, 58.2, 57.5, 59.9, 61.2, 60.4; Benchmark prices (same dates): 4100, 4150, 4090, 4210, 4240, 4200, 4290, 4350, 4320, 4400, 4460, 4430.
Results — Beta (β) = 1.936; Correlation = 0.989; R² (share of moves explained by the market) = 0.978; Return periods = 11; Average stock return per period = 1.406; Average benchmark return per period = 0.716.
Frequently asked questions
What does a beta of 1.2 mean?
The stock has tended to move 1.2% for every 1% move in the market.
Which benchmark should I use?
A broad index such as the S&P 500 for U.S. stocks.
How many data points do I need?
At least 20; analysts often use 60 monthly or 104 weekly returns.
What formula does the Stock Beta Calculator use?
Returns: rₜ = Pₜ ÷ Pₜ₋₁ − 1 for the stock and the benchmark.