The secret science behind subtitle speed

In subtitling, precision is everything.

Every second a subtitle remains on screen is carefully calculated to make sure you can read without missing the visual action.

This precise timing is the secret behind a truly smooth viewing experience.

Have you ever noticed how precisely subtitles appear and disappear?

It’s not arbitrary.

The speed limits aren’t guesswork. They’re governed by scientific principles designed to prevent cognitive overload.

Reading vs. Watching

When you watch content with subtitles, your brain is performing a complex dual task:

• Reading: Processing the text at the bottom of the screen.
• Watching: Tracking the action, facial expressions, and visual cues.

If the subtitle stays on screen for too long, your brain finishes reading and is forced to wait, distracting you from the scene.

If it’s too fast, you miss the plot.

The secret of professional subtitling lies in balancing these two tasks, allowing the text to disappear the exact moment you finish reading.

The Eye-Tracking Secret

How do experts measure actual reading speed?

They look at how the eye moves:

• Fixation: The moment your eye stops on a word to actually process and understand it (the true reading time).
• Saccade: The rapid jump the eye makes between fixation points.

The human eye can only perform a limited number of fixations per second. Our job as subtitling experts is to make sure the text remains exactly long enough to cover the necessary fixation time, and no longer.

Characters Per Second (CPS)

We don’t use Words Per Minute (WPM).

The global standard is the far more precise metric: Characters Per Second (CPS).

This metric accounts for the actual length of words, not just the count, ensuring accuracy across different languages.

This number makes sure that for every character we display, the viewer has the optimal processing time.

Smooth immersion

The science of reading speed is about viewer comfort and immersion.

Subtitlers use CPS to achieve three key goals:

• Maximize comprehension: Ensure the text is readable by the target audience.
• Maintain engagement: Allow the viewer to spend maximum time focused on the image and the narrative.
• Ensure accessibility: Level the viewing field, so everyone can enjoy the content without stress.

The goal is to create the best viewing experience possible.

P.S. Interested in mastering the why and the how of these professional standards? My upcoming course on TranslaStars will cover these technical limits and expert strategies in detail. Follow the link for further information.

Image by rawpixel on Freepick