Two different settings decide how much text your viewers see at once. Size is how big the letters are. Characters per line and max lines decide how the text is split into subtitles. This guide shows where each one lives, what happens when you change it on an existing track, and how to read the two warnings the editor gives you.
Change the font size
Open Style in the editor toolbar and move the Size slider, from 5 to 26 px. You can also drag one of the four corner handles of the subtitle in the video preview; that does the same thing. The starting size depends on the shape of the video: 14 px for landscape, 13 for square, 12 for portrait and 10 for full-height portrait, because the same text needs less room on a tall, narrow frame. Style presets never change the size.
Change characters per line or max lines on an existing track
Click Layout in the editor toolbar. The panel has two controls: Max lines (1 or 2) and a Chars per line slider. Its range scales with the language's default and the video's aspect ratio, from a quarter of the default up to 175% of it.
As soon as you change a value, a warning appears: All manual edits will be overwritten and cannot be restored. No credits will be used. Click Apply Changes and Fluen re-splits the whole track with the new settings in a few seconds; the panel shows "Reprocessing..." while it works. If you have already corrected text by hand, export a copy first, or make the layout change before you start editing.
Set them before uploading
On the upload screen, expand Subtitle settings: Max lines per caption (1 or 2) and Max characters per line (20 to 60). The default is 42 for English on a landscape video, 32 on tall portrait, 30 on square and 26 on full-height portrait; other languages have their own defaults, based on the conventions of the major style guides. For translations that must follow a client's fixed value, add a per-language override in Workspace Settings under Subtitle Limits: see Set your default subtitle specifications.
Reading the warnings
- Red edges on a subtitle in the preview. The text is wider than the video frame at its current size and position, and would be cut off in a burned-in export. Lower the characters per line, reduce the size, or move the caption: see Position captions on the video.
- The CPS number under a cue. Every cue in the list shows its reading speed in characters per second. On translation tracks, a yellow warning appears when a cue is faster than the comfortable pace for that language (20 characters per second for most languages, lower for some). The tooltip suggests the fix: rephrase, or give the cue more time on the waveform. Translations already go through AI Wordsmith, which shortens most of the long ones automatically; the warning flags what is left.
Which one should I change?
| If... | Change |
|---|---|
| The text is hard to read on a phone | Size (bigger), and perhaps a Letterbox background |
| Subtitles cover too much of the picture | Max lines to 1, or a smaller size |
| Lines look too long for the frame, or show red edges | Chars per line (lower) |
| A client's style guide sets a line length | Chars per line on upload, or a Subtitle Limits override for that language |
| Subtitles flash by too quickly | Nothing in Layout: extend the cue on the waveform or shorten the text |