Delta measures how much an option moves per $1 in the underlying; gamma measures how fast delta itself changes. Together they explain an option’s responsiveness — and the difference matters most on 0DTE.

Delta: the speed

Delta is your option’s current sensitivity to price — a 0.50-delta option gains ~$0.50 per $1 up-move. It’s also a rough probability of finishing in the money. Delta is the first thing to check for whether an option will respond to a move.

Gamma: the acceleration

Gamma tells you how fast delta changes as price moves. High gamma means delta swings quickly, so the option gets more (or less) responsive fast. Think of delta as speed and gamma as acceleration: gamma is why an option’s behavior can change dramatically during a move, especially near the money.

Delta is how fast your option moves now; gamma is how fast that speed changes. Speed and acceleration — and on 0DTE, the acceleration is extreme.

Why it matters on 0DTE

On 0DTE, gamma is at its maximum, so delta swings violently — a near-the-money option’s delta can jump from 0.2 to 0.8 on a modest move. That’s why 0DTE options are so responsive and so whippy. Understanding both Greeks explains the sharp, fast behavior that defines the 0DTE tape.