Caption Fit Lab

Read the cue before you burn it in.

Check characters per second, preview a 9:16 frame, and export an SRT. The file stays on this device.

Speed checker

CPS, line length, line count, overlaps.

Open

9:16 preview

A phone frame, a local video, and the caption.

Open

Fix timing

Close overlaps and download the file.

Open

On this device

The calculation stays in this browser. The worked example on the guide is written in HTML so the inputs and the result can be read without running the script.