Subtitle line length: how many characters per line, and where to break
In short: Netflix allows 42 characters per line and two lines per subtitle for English. BBC broadcast subtitles allow 37 characters per line, a Teletext limit. For vertical video, shorter lines are safer because app buttons and captions cover the edges of the frame. Break lines after punctuation or before a conjunction or preposition, and never between words that belong together.
How many characters per line should a subtitle have?
For English streaming delivery, 42 characters per line is the common limit, and it is the number Netflix sets. BBC broadcast subtitles are limited to 37 characters because of Teletext. Characters include spaces and punctuation.
| Where the subtitles will play | Line length | Lines | Source |
|---|---|---|---|
| Netflix, English | 42 characters | 2 max | Netflix English (USA) Timed Text Style Guide |
| BBC broadcast | 37 characters | 2 max | BBC Subtitle Guidelines, Teletext constraint |
| BBC online, 16:9 video | 68% of the video width | 2 max | BBC Subtitle Guidelines |
| BBC online, 9:16 video | 90% of the video width | 3 max | BBC Subtitle Guidelines |
The BBC's online rule is a width, not a character count, because proportional fonts make some characters wider than others. Other languages have their own limits; Netflix publishes a separate guide for each language it supports.
Subtidy's presets: Streaming uses 42 characters, Broadcast uses 37, and Social vertical uses 28. The 28 character limit is Subtidy's own choice for 9:16 video, not a platform rule: at a readable caption size, a narrow vertical frame fits fewer characters, and the right edge is covered by like and share buttons on TikTok and Reels. Subtidy is not affiliated with Netflix or the BBC.
How many lines should a subtitle have?
Two lines at most for landscape video. Netflix asks for a maximum of two lines and prefers one line when the text fits. The BBC recommends two lines for 16:9, 4:3 and 1:1 video, and up to three for vertical 9:16 video.
When a subtitle needs a third line in landscape video, it is usually better as two subtitles, one after the other.
Where should you break a subtitle line?
Break after punctuation where you can. Otherwise break before a conjunction or a preposition. Netflix and the BBC both list words that should stay on the same line. Between them, keep together:
- an article and its noun (the + table)
- an adjective and its noun
- a first name and a last name
- a pronoun and its verb (they + will come)
- the parts of a verb (will + have been)
- a preposition and the phrase that follows it (on + the table)
Compare two ways of breaking the same subtitle:
Poor: I left my keys on the
kitchen table before we went out.
Better: I left my keys on the kitchen table
before we went out.The first splits the from kitchen table. The second breaks before before, where a speaker would naturally pause, even though the lines are less even.
The BBC puts it plainly: good line breaks matter, but when you cannot have everything, well-edited text and good timing matter more.
Should the two lines be the same length?
Many subtitlers keep the two lines close in length, and some house styles prefer one line slightly longer than the other. Either way it is a style choice rather than a Netflix or BBC rule, and grammar comes first: a natural break with uneven lines beats an even split in the middle of a phrase.
Why do automatic transcripts produce long lines?
Speech-to-text tools cut subtitles where the speaker pauses, not at a line length. A single cue can hold a whole sentence of 80 or more characters on one line. Some tools have settings for a maximum line width, but many exported files still need the lines rebalanced and the longest cues split before delivery.
Line balancer
Type or paste a subtitle, choose a limit, and see how Subtidy would break it. This runs the same line-balancing code as the workspace, in your browser.
How Subtidy rebalances a whole file
- Rebalance line breaks rewraps each cue into as few lines as fit the limit, choosing the break that keeps the lines closest in length and preferring breaks after punctuation, including Urdu and Arabic punctuation.
- Split overfull cues turns a cue that needs more lines than allowed into consecutive subtitles, and shares its time between them by the length of each part.
- Two-speaker lines that start with a dash are left as they are when they already fit.
- Every changed cue is marked Edited or Split in the cue list, and the QC report shows long lines and too many lines before and after.
What it does not do: Subtidy does not analyse grammar. It balances line lengths and prefers punctuation, so it can break inside a phrase. Put the kitchen table example from above into the line balancer and it splits kitchen from table, where an editor would break before before. The BBC recommends placing line breaks by hand for this reason. Use the automatic pass to fix a whole file quickly, then skim the Edited cues and move any break that splits a phrase.
Rebalance the lines in your file
Open an SRT, WebVTT or ASS file. It is processed in your browser and never uploaded. Free for one file at a time, with SRT export.
Sources
- Netflix Partner Help Center, English (USA) Timed Text Style Guide, updated 19 December 2025: character limitation, line treatment.
- Netflix Partner Help Center, Timed Text Style Guide: General Requirements: line treatment.
- BBC, Subtitle Guidelines, version 1.2.5, March 2026, section 3 Line breaks.