Subtitle Converter

SRT and WebVTT: what changes

SRT and WebVTT are both plain-text timed-caption formats. An SRT cue normally has a numeric sequence, a time range with comma-separated milliseconds, and one or more text lines. WebVTT starts with the required WEBVTT header and uses a dot before milliseconds. According to MDN’s WebVTT format guide, WebVTT cue payloads may span multiple lines and an empty line ends the cue.

The converter parses cues into a neutral local model before writing the destination format. It does not merely replace every comma or dot in the document. That matters because punctuation in subtitle text must remain untouched.

Validation before conversion

Each timing line must contain a start and end separated by -->. Minutes and seconds must be between 00 and 59, milliseconds must have exactly three digits, and the end must be later than the start. A cue also needs at least one non-empty payload line. The validator reports the source block containing each problem so you can correct the original rather than receiving a partial file that only looks complete.

WebVTT allows optional cue identifiers and positioning settings. The W3C WebVTT specification defines timed text tracks for captions, subtitles, descriptions, chapters and other time-aligned metadata. SRT has no standard equivalent for WebVTT NOTE, STYLE, REGION blocks or cue-position settings. When converting VTT to SRT, this tool omits those unsupported structures and displays a warning. Cue timing and payload text remain intact.

A safe conversion workflow

1. Keep the original subtitle file as your source copy.
2. Open or paste it and correct every reported malformed block.
3. Preview the first cues and confirm that line breaks and timing order look intentional.
4. Download the destination file and test it with the actual player or publishing platform.
5. Check reading speed, synchronization, speaker labels and accessibility separately; format conversion cannot judge editorial quality.

Privacy and limits

The subtitle text is read, parsed and generated in your browser. It is not bound to a Livewire property, submitted to the server or included in the funnel URL. During the multi-step flow, the current source is stored temporarily in this browser’s IndexedDB so the next pageview can restore it. Starting over removes that saved record.

The 5 MiB limit bounds parsing and browser storage. This converter covers SRT and WebVTT only; it does not translate dialogue, transcribe audio, shift timestamps, merge tracks or convert styling from ASS/SSA. Conversion preserves the text supplied, including markup-like characters, and the preview renders it as text rather than executable HTML.