Back-to-School Refresh: Subtitles

As part of our back-to-school refresh blog series, today’s blog will be going over some subtitle guidelines and why they are necessary. Despite playing an important role, guidelines do make subtitling that bit more difficult. This is why subtitling is such an art, and why a machine can’t produce the same high-quality subtitles that a professional human linguist can.

This blog will delve into some of the guidelines a little deeper and help to clarify what role they play in the quality of subtitles. Let’s get straight to it:

Syncing subtitles

It’s important to try and sync the subtitles to the visuals and the audio as best as possible. This is much easier said then done, however. By syncing the subtitles with the video, they will appear when the character’s lips are moving for example. This makes them feel more natural. The subtitles should also be in sync with the audio as much as possible too. Despite not necessarily understanding the audio, this will help the viewer read the subtitles.

Enough time to read

It is recommended that the subtitle should appear on screen for between one and seven seconds. This allows enough time for the viewer to read the subtitle. The time will depend on the subtitle’s CPS (characters per second).

The recommended figure is around 17 CPS, as this is based on the average reading speed.

Consider the visuals

For Latin alphabet languages, it’s advised that the character limit per line is 42. On top of this, a subtitle is recommended to have no more than 2 lines. This may not sound so bad, but for languages such as German for example where the words are considerably longer than English, this can be quite the challenge. So why are these guidelines necessary? It restricts the subtitle, to avoid it covering too much of the visuals.

On-Screen text

If there is text superimposed on the video, this is known as ‘on-screen text’. Common examples of this are ‘two years later…’ or maybe interviewee names. This can be subtitled, above or below the original text, however this covers more of the video. Alternatively, if the text was added as editable text, this could be changed on the video itself.

This decision would of course depend on the budget, as the first option is considerably cheaper than the latter.

Keep Subtitles Clear

Due to the restricted time and space with subtitles, it’s important to keep them clear and concise. Removing any unnecessary hesitations could help achieve this. Although it’s always worth considering whether the hesitation has an intended effect or not.

Time to Breathe

There is also a guideline which advises that there should be at least 2 frames between each subtitle. Around 24 frames are drawn each second, so this really is a very short gap. It may seem insignificant; however this gap allows our brains to refresh and acknowledge the new subtitle effectively.


Where we position subtitles is also key. The positioning must remain as consistent as possible. Subtitles can be moved to the top of the screen, so that it doesn’t interfere with the visuals.

However, you should try to avoid going from the top to the bottom and back to the top where possible.

This is because it makes it difficult for the viewer to follow the subtitles. If you need to change the location, extend the subtitle length so that the viewer can catch up.

We hope you have found this useful! We have of course only scratched the surface though! If you’d like to learn more about subtitling, please get in touch and we’d happily talk to you about subtitling your content.

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