How to use
- Drop in or paste an SRT or VTT subtitle file — the tool auto-detects the direction from the file extension.
- Choose the output format (SRT to VTT or VTT to SRT) and enter an optional time shift in seconds.
- Click Convert to parse the cues, reformat the timestamps, and apply the shift.
- Copy the converted subtitles or download them with the correct .srt or .vtt extension.
Frequently asked questions
What is the difference between SRT and VTT?
SRT (SubRip) and VTT (WebVTT) are the two most common subtitle formats. They are almost identical, but SRT uses a comma before the milliseconds in timestamps while VTT uses a dot and begins with a WEBVTT header. This converter handles both formats automatically in either direction.
How does the time shift work?
Enter a number of seconds — a positive value delays the captions so they appear later, and a negative value makes them appear earlier. Every cue's start and end time is moved by that amount, and any time that would fall below zero is clamped to the start (00:00:00).
Are my subtitle files uploaded anywhere?
No. Parsing, converting, and re-timing all happen locally in your browser using JavaScript. Your SRT and VTT files never leave your device and are never sent to any server, so your captions stay completely private.
Which subtitle formats are supported?
The tool converts between SRT (.srt) and VTT (.vtt) files. It reads standard timestamps like 00:00:01,000 (SRT) and 00:00:01.000 (VTT), including the shorter mm:ss.mmm VTT form, and reserializes them cleanly for the target format.
Is there a file size or length limit?
There is no fixed limit imposed by the tool. Because everything runs in your browser, very large subtitle files are only bound by your device's available memory, so typical movie and episode subtitles convert instantly.
Will converting change my caption text or quality?
No. Your caption text is preserved exactly as written — only the timestamp format and, if you request it, the timing are changed. Cue indexes are renumbered sequentially, and the output uses the correct comma or dot and header for the target format.
About this tool
Free online subtitle converter: change SRT to VTT or VTT to SRT and shift caption timing. Runs 100% in your browser — no uploads, files stay private.