Volatility measures how much a stock's price fluctuates. Annualized volatility (the standard measure) is the standard deviation of yearly returns, expressed as a percentage. Higher vol means larger swings — more profit potential AND more loss potential. It's a foundational input for options pricing, risk-adjusted return metrics, and position sizing.

A formula that estimates volatility from daily high-low range: σ ≈ ln(High/Low) ÷ (2 × √ln(2)). It's more efficient than close-to-close volatility because it uses intraday range. Particularly useful when you only have OHLC data without intraday tick data. The calculator uses this when computing volatility from a stock's 52-week range.

Average True Range measures average daily price movement, including overnight gaps. A stock with ATR = $3 typically moves $3 per day. Useful for: stop-loss placement (e.g. 2× ATR below entry), comparing how 'jumpy' two stocks are, and position sizing relative to current volatility regimes.

Beta measures volatility relative to the market (S&P 500). Beta of 1.0 = moves with the market. Beta > 1 = more volatile (e.g. tech stocks at 1.3–1.8). Beta < 1 = less volatile (e.g. utilities at 0.4–0.7). Beta-adjusted volatility = market vol × stock beta — useful for portfolio risk modeling when individual-stock vol data is unavailable.

Based on the volatility, the calculator shows expected price ranges with 68%, 95%, and 99.7% confidence (1, 2, and 3 standard deviations). Example: a stock at $100 with 20% annual vol → ~95% chance of staying within $80–$120 over a year. Useful for setting stop-loss levels that won't get hit by normal volatility.

The math is the same, but inputs differ. Stock vol uses share prices, ATR in dollars, beta vs market index. Forex vol uses currency-pair quotes, ATR in pips, no beta concept. Both produce annualized % volatility — directly comparable across asset classes. Use Stock Volatility for equities; Forex Volatility for currency pairs.