The Average True Range (ATR) measures how much price moves, on average, over a period — a direct read of volatility. Using it to set stop distance means your stop is proportional to the day's real range, instead of a fixed number that's wrong on most days.
Why fixed stops fail
A fixed stop — “always risk 30 cents” — is too tight on a high-volatility day, where normal noise runs it before your idea plays out, and too loose on a quiet day, where you give back more than the range warrants. Volatility changes day to day and hour to hour; a stop that doesn't adapt gets whipsawed or oversized.
The ATR method
Set your stop a multiple of ATR away from your entry — commonly around 1× to 1.5× ATR for a scalp, adjusted to the setup. On a high-ATR day the stop is wider (giving the trade room to survive the bigger swings) and you size down to keep dollar-risk constant; on a low-ATR day it's tighter. The stop breathes with the tape. Then translate that underlying distance into an option-premium stop via delta.
ATR makes your stop as wide as the day is — no wider, no tighter. Volatility sets the distance; your dollar-risk stays constant via size.
The honest limits
ATR is backward-looking — it measures recent volatility, which can jump (a catalyst) faster than ATR updates. Use it as a baseline for stop distance, then place the actual stop at a logical level (beyond the wall, below the swing low) rather than a raw ATR number in the middle of nowhere. It's a sizing tool that keeps risk consistent, and it pairs with the ATR expected-range read for the day's context. NoVo sizes stops to volatility and structure for the same reason: a good stop fits the day, not a habit.