Turn a lyric into caption chunks sized for the screen, timed from your tempo, and export them as text or SRT.
On-screen captions have a hard limit: too many characters and they overflow, too few milliseconds and nobody can read them. Doing that maths by hand for a three-minute song is an hour of work and you will get it wrong twice. This tool times each line from your tempo, groups them into chunks that respect a character cap and start on a bar, and hands you plain text plus a subtitle file.
Run it and the chunks show up here.
Why captions need their own timing
Captions are not lyric sheets. A lyric sheet can hold sixteen lines; a caption has room for around sixty characters before it starts covering the thing you want people to look at. And a caption that appears for half a second is worse than no caption, because the eye starts reading and does not finish — the viewer notices the failure rather than the words.
The timing has to come from somewhere, and tempo is the only thing you have before the master exists. One line at four beats and 96 BPM is 2.5 seconds, which is a comfortable caption. The same line at 150 BPM is 1.6 seconds, which is tight. The same line at 72 BPM is 3.3 seconds, which is roomy enough for two lines in one caption — and that is exactly where you save the most space.
How to use the result
- Anything under 0.8 seconds is flagged. Merge it with the chunk before it rather than shipping an unreadable caption.
- The character cap is a working default, not a rule. Vertical video needs fewer characters than horizontal; a caption at the bottom of a 9:16 frame has less room than one under a 16:9 frame.
- Chunks never split a line of lyric in half. If a single line is longer than your cap, it gets its own chunk and is flagged — shorten the line instead.
- The SRT is an estimate. Once you have the master, nudge the timings against the actual audio; the structure will be right even if the exact milliseconds are not.
Questions people ask
- Where do the timings come from?
Lines times beats per line, divided by tempo. Blank lines in your lyric are treated as a one-bar gap. It assumes the singing starts where you told it to.
- Why does a chunk start on a bar?
Because a caption landing off the beat looks like a mistake even when nobody can say why. Starting on a bar boundary keeps the text and the music moving together.
- Can I get WebVTT instead of SRT?
The SRT is close enough to convert by hand — change the header and swap commas for periods in the timestamps. Both formats are plain text.
- Is the download safe?
It is generated in your browser from a Blob and saved straight to your disk. Nothing is uploaded anywhere.
What this tool does not do. It estimates timings from a tempo you typed; it does not listen to your audio, so every timestamp is approximate until you check it against the master. It cannot read your video frame and does not know how large your captions will be rendered. Nothing is uploaded; everything runs in your browser and works offline. See the site disclaimer. Written by Nico, who builds these tools and writes about writing at WrittenTone.