Subtitle line length guidelines
The 42-character rule is the most-quoted subtitle guideline in the world. This guide explains where it came from, when it applies and where it does not.
The classic 42-character rule
For decades, subtitle guidelines have recommended a maximum of 42 characters per line and two lines per cue. This produces a maximum of 84 characters per cue.
The number comes from the era of broadcast television and DVD — a time when the standard screen was 4:3 aspect ratio, subtitle fonts were fixed size and viewers watched from across a room. 42 characters fit comfortably on screen without the line becoming unreadable or running off the edge.
Modern guidelines
Modern screens are wider and higher resolution, but the 42-character guideline persists because it remains a good proxy for readability. Different content types have slightly different targets:
| Context | Max characters/line |
|---|---|
| Broadcast television | 37–42 |
| Streaming (Netflix, Disney+) | 42 |
| Web video (HTML5) | 42 |
| Mobile-first content | 32 |
| Children's content | 32 |
Lines per cue
The standard is maximum two lines per cue. Three-line cues are almost always a sign that the cue should be split. Four-line cues are almost never appropriate.
Exceptions:
- Poetry or song lyrics where the line breaks are part of the content.
- Dense technical content where a single thought genuinely does not fit in two lines.
- Pre-lingual deaf or accessibility-focused subtitles where complete sentences matter.
For standard dialogue subtitles, two lines is the ceiling.
Why line length matters
Long subtitle lines hurt in three ways:
- Reading speed. A line that is too long takes longer to read, which means the viewer has less time to also watch the picture.
- Eye tracking. Viewers track subtitles line by line. Long lines require more saccades (eye jumps), which feel exhausting over a long video.
- Screen coverage. Long lines cover more of the picture, which is distracting. The subtitle should feel like it is floating over the video, not blocking it.
- Split the cue. If the dialogue has a natural pause, split the long cue into two shorter cues. This is almost always the best option.
- Shorten the dialogue. Subtitle is not a transcript. Condense where possible: remove filler words, use contractions, drop redundant phrases. As long as the meaning is preserved, shorter is better.
- Re-break the line. If you have two lines in a cue, distribute the characters more evenly. A cue with 40 characters on line one and 20 on line two is harder to read than a cue with 30 and 30. Aim for balanced lines.
- Spaces count. A line with 40 letters and 10 spaces has 50 characters and counts as 50.
- Punctuation counts. A comma adds cognitive load, so it "counts" as a character even though it is not a letter.
- CJK characters are wider. In Chinese, Japanese and Korean subtitles, a single character is much wider than a Latin letter. The 42-character rule is for Latin scripts; CJK subtitles use different rules (often 12–16 characters per line).
- HTML tags don't count.
<i>,</i>and similar tags are display markup, not text. Do not count them. - 90% of lines should be within 42 characters.
- 9% of lines can be 43–48 characters if the content genuinely needs it.
- 1% of lines can exceed 48 characters if there is no other option (unusual names, technical terms, quotes).
How to shorten long lines
If a cue has a line longer than the target, you have three options:
Character counting subtleties
Not all characters are equal for reading purposes:
How to check line length
Use the Line Length Checker to find every line that exceeds the limit. It runs in your browser and lists every overlong line with cue number and current length.
For count of lines per cue, use the Line Counter.
Realistic guidelines
Strict adherence to 42 characters per line is not always possible. In practice:
The goal is not perfect compliance — it is readable subtitles. Use the guideline as a tool to catch mistakes, not as a rule to obsess over.