# Stock Beta Calculator

URL: https://speedycalculator.com/calculators/finance/beta-stock/
Last updated: 2026-10-25

> The stock beta calculator works out a stock's beta – how strongly its returns move with the market – from a series of its prices and a benchmark index's prices, along with the correlation and R².

## Inputs

- Stock prices (oldest first)
- Benchmark prices (same dates)

## Results

- Beta (β)
- Correlation
- R² (share of moves explained by the market)
- Return periods
- Average stock return per period
- Average benchmark return per period
- Interpretation

## Formula

```
Returns: rₜ = Pₜ ÷ Pₜ₋₁ − 1 for the stock and the benchmark
Beta = covariance(stock, benchmark) ÷ variance(benchmark)
R² = correlation²
```

## Explanation

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.

## Worked 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.

## FAQ

**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.


## Sources

- [Corporate Finance Institute – financial ratios](https://corporatefinanceinstitute.com/)