The core difference
SRT uses numbered caption blocks and comma-based milliseconds. WebVTT starts with a WEBVTT header and uses period-based milliseconds.
For simple captions, both formats can contain the same spoken text and timing. The difference matters most when a platform expects one format or when a web player uses VTT-specific features.
When to use SRT
Use SRT when you need broad compatibility with editors, translators, upload forms, and simple localization workflows. It is easy to inspect, easy to diff, and easy to repair.
- Video editing handoff.
- Translation and review workflows.
- Simple YouTube or course captions.
- Client delivery where the platform is unknown.
When to use VTT
Use VTT when the destination is a web video player or a system that specifically requests WebVTT. VTT can support cue settings, comments, and metadata that basic SRT does not include.
- HTML video players.
- Web apps and learning platforms.
- Caption workflows that need VTT cue metadata.