Subtitle Line Breaker

What this tool does

This tool rewraps subtitle lines to a character limit, for example 42 characters and two lines, without splitting words. It also reports reading speed in characters per second and line length for every subtitle, so you can find lines that are too fast to read. Presets follow the Netflix English guide and common vertical video practice.

How to rewrap subtitle lines

Select Choose files and add subtitle files, or use Paste text.
Choose a Preset, or set Maximum characters per line and Maximum lines per subtitle yourself.
Select Rewrap lines.
Read the Reading speed report: the share of subtitles over each limit, the reading speed of all subtitles and a table of subtitles to check.
Select Download for one file or Download all (ZIP) for several files.

Options explained

Preset fills in characters per line, lines and reading speed. General (42 × 2, 17 CPS) is the default.
Line breaks: Rewrap all lines breaks every subtitle again; Keep lines that already fit changes only subtitles that are too long or have too many lines; Join into one line puts each subtitle on one line.
Line shape: Balanced lines keeps lines about the same length; Longer bottom line makes the top line shorter.
Maximum reading speed (CPS), Minimum duration (ms) and Maximum duration (ms) set the limits of the report: 17 CPS, 700 ms and 7000 ms by default.
Lengthen fast subtitles is off. When on, a subtitle that is too fast is extended into free time before the next subtitle, up to the maximum duration. It never overlaps the next subtitle.
The output keeps the input format and is saved as UTF-8. SRT and ASS files keep their line endings.

Example

With the default options:

1
00:00:01,000 --> 00:00:04,000
When we get to the station, call your mother and tell her.

Output:

1
00:00:01,000 --> 00:00:04,000
When we get to the station,
call your mother and tell her.

Format notes and limits

Reads SRT, VTT, ASS, SSA and SBV. ASS drawings and comment lines are not changed or counted.
Sources of the presets: Netflix, English (USA) Timed Text Style Guide (42 characters per line, maximum two lines, adult programs up to 20 characters per second); Limecraft, best practices for subtitling vertical video (at most 25 characters per line, 3 lines).
Up to 50 files, 20 MB per file and 200 MB in total.
To fix overlaps and durations, use Fix subtitles. To remove sound notes before counting, use Clean subtitles.

Questions

What does the line breaker change?

Only spaces and line breaks. Words, punctuation and tags such as italics stay exactly as they are, in the same order.

How are lines broken?

Never inside a word. Lines are balanced in length, a single short word is not left alone on a line, and a break after a comma is preferred. Chinese, Japanese and Korean text breaks between characters, never before closing punctuation.

What happens to dialogue with two speakers?

Lines that start with a dash stay on their own lines, one per speaker.

How is reading speed counted?

Characters per second (CPS) is the number of characters divided by the seconds on screen. Spaces and punctuation count; line breaks and tags do not. Turn off Count spaces to leave spaces out.

Where do the presets come from?

Netflix English uses 42 characters per line, two lines and up to 20 characters per second for adult programs, from the Netflix English (USA) Timed Text Style Guide. Vertical video uses at most 25 characters and 3 lines, from Limecraft's best practices for subtitling vertical video. General uses 42 × 2 and 17 CPS.

Does it split subtitles that are too long?

No. A subtitle that does not fit in the allowed lines is counted in the report and left as one subtitle. Shorten it or split it in a subtitle editor.

Are my files uploaded?

Your files are processed in your browser and are not uploaded to our servers.

Drop subtitle files here

Options