# 180-degree rule

Canonical URL: https://www.cineoboard.com/glossary/180-degree-rule

The 180-degree line is an imaginary line between subjects. Crossing it reverses screen direction. Mark it on the board before you add coverage.

Last updated: 2026-09-13

The **180-degree line** (axis of action) runs between the subjects. Keep the camera on one side and screen direction stays readable: A stays left, B stays right. Cross the line and they swap. Audiences feel it as a mistake even when they cannot name it.

On a storyboard, draw the line once on the master and obey it on every over and single. If you *must* cross, board the crossing shot so the cut is motivated (a camera move, a character walk).

Craft: [continuity and eyelines](/blog/storyboard-continuity-eyelines) · [180-degree rule on a storyboard](/blog/180-degree-rule-on-a-storyboard).

## Why generators break it

A model that draws frames independently does not share a floor plan. Humans have to impose geography. [AI generators](/ai-storyboard-generator).

Related: [eyeline](/glossary/eyeline), [coverage](/glossary/coverage), [over the shoulder](/glossary/over-the-shoulder).

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