How the timing is worked out
Subtitles need to stay on screen long enough to read. The default mode counts the visible characters in each caption and divides by a reading speed — 15 characters per second is the usual broadcast guideline — then clamps the result so nothing flashes past or overstays. Short captions get a floor, long ones get a ceiling.
If your script is meant to match footage you already have, switch to Fit a total duration and type the length of the video. The captions are then spread across that runtime in proportion to how much text each one holds, so the last one ends exactly on time.
SRT or VTT — which do you need?
- .srt — SubRip. The safe default. YouTube, Premiere, VLC, Resolve and every social platform accept it.
- .vtt — WebVTT. What HTML5
<track>elements want, so use it for subtitles on your own website.
Both files are generated at once from the same timings, so you can grab either — or both.
Line wrapping matters more than it looks
A caption that runs off the edge of the frame is worse than no caption. The wrap setting breaks each one at a word boundary once it passes the character limit — 42 is the broadcast convention for a comfortable two-line caption. Text without spaces, such as Chinese or Japanese, is broken by character instead.
Frequently asked questions
How do I fix the timing afterwards?
Change the reading speed, the gap or the start offset and the file regenerates instantly — the preview you see is the exact file that downloads. For fine adjustments to individual lines, open the .srt in any text editor; the format is plain text.
Can I use this to caption a video I already have?
Yes. Pick 'Fit a total duration', enter the video's length in seconds, and the captions are distributed across it. Then use the button to send them to the subtitle burner and check the result frame by frame.
What if my text is one long paragraph?
Switch 'One caption per' to Sentence. The text is split at full stops, question marks and exclamation marks, including the Chinese and Japanese equivalents, so each sentence becomes its own caption.
Is my text uploaded?
No. The captions are generated by JavaScript in your browser — nothing is sent anywhere.
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