Last updated June 6, 2026 (UTC)
SRT to VTT converter guide
Converting SRT to WebVTT is more than renaming the file. Use our free SRT to VTT converter or read the pitfalls below before you upload to an HTML5 player or YouTube.
Required changes for valid WebVTT
- Add a WEBVTT header on line one.
- Convert comma decimals in timestamps to dots.
- Remove or flatten SRT-style numbering if your pipeline expects cue IDs differently.
- Validate overlaps and reading speed for your destination preset.
Run your file through CaptionPass — free caption converter with a full QA report.
Convert & fix free →Common failures after “conversion”
- Missing WEBVTT header — HTML5 players reject the file silently.
- Comma decimals left in timestamps — cues drop one by one.
- Styling tags from other tools — stripped or mis-parsed on social platforms.
Deeper format comparison: SRT vs VTT.
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Upload on CaptionPass, pick a delivery preset, and download upload-ready output with optional enhanced formatting — free tier, no account required.
Convert & fix free →More guides
- Free online caption converter — SRT, VTT, and delivery QAHow CaptionPass works as a free caption converter with upload-ready and enhanced exports, platform presets, and explainable fixes. Try the same presets on the homepage tool or Quick fix before you open a Pro project.
- SRT vs VTT — when each format silently failsComma vs dot timestamps, WEBVTT headers, and where YouTube, TikTok, and HTML5 bite. Run either format through the homepage tool or POST /api/v1/process to see explainable fixes before delivery.
- Caption file encoding — UTF-8, BOM, and garbled textWhy uploads show mojibake or blank cues: UTF-8 vs legacy encodings and quick fixes. CaptionPass ingest reports flag encoding issues in the workbench Checks tab and v1 processing errors.
- Burned-in vs soft subtitles — what to deliver whenOpen captions burned into the picture vs separate SRT/VTT tracks — tradeoffs for editors and clients. Pro users can mux or burn-in via v1 render jobs after sidecar QA in the workbench.
- Reading speed for captions — CPS, line length, and platformsCharacters per second, lines per cue, and where YouTube, TikTok, and HTML5 push back. Platform presets in the dashboard and v1 API apply the same CPS and line-length rules automatically.
- YouTube caption upload issues — silent rejection and timingWhen Studio accepts a file but captions vanish: format, line length, drift, and how to validate before publish. Export with the YouTube preset from Deliver or v1 before you upload to Studio.
- YouTube rejected my SRT — invalid file and Studio errorsWhen YouTube Studio blocks an SRT upload: encoding, index gaps, bad timestamps, and how to validate before you retry. Quick fix and the homepage tool surface the same diagnostics as a failed v1 run.
- Caption timing drift after export from Premiere or DaVinciWhy captions slip after NLE export: frame rates, timecode starts, and how to normalize before YouTube or client delivery. Pro drift diff in the workbench compares revisions after you re-import from an NLE.
- CaptionPass vs generic subtitle convertersFormat swap tools vs delivery QA: explainable fixes, platform presets, and when each approach fits your workflow. CaptionPass adds Checks, receipts, and handoff packs on top of one-shot homepage conversions.
- CaptionPass vs Subtitle EditDesktop authoring vs delivery QA: when to use Subtitle Edit for editing and CaptionPass for platform-safe validation and API automation. Ship Subtitle Edit exports through the dashboard workbench or v1 API for final QA.
- Caption QA API for CI/CD pipelinesAutomate SRT and VTT validation in GitHub Actions or your build pipeline with POST /api/v1/process and Bearer API keys. Keys and usage meters live under dashboard Automate alongside export webhooks.
- TikTok subtitle format — short lines, CPS, and clean SRTVertical video reading speed, styling stripped on upload, and export settings that survive TikTok delivery. Use the social-shorts handoff profile or TikTok preset from Deliver before upload.
- Why your captions are not showing — a triage guideHTML5, YouTube, and TikTok checks when subtitles vanish after upload. Cross-check workbench preflight and History receipts to confirm what CaptionPass actually exported.
- Fix overlapping subtitlesWhat overlap means and why some players drop overlapping cues. CaptionPass flags overlapping_cues in Checks and can auto-fix via Fix again or v1 process.
- TTML and DFXP — broadcast-style timed text on the webNamespaces, timing, styling stripped in practice, and when TTML is the right interchange vs SRT or WebVTT. Convert inbound TTML through v1 or the homepage tool when clients deliver broadcast sidecars.
- CaptionPass JSON IR and the developer-json presetLossless-ish cue interchange for tooling: when to use JSON IR, version tag, and how it pairs with the HTTP API. Request the developer-json preset from POST /api/v1/process or export it from the workbench.
- Timecode, frame rate, and caption syncWhy captions drift or jump: drop-frame vs non-drop, fractional frame rates, and export settings that survive upload. Pro drift panel and v1 diff help confirm sync after re-export from an NLE.
- WCAG-minded captions — reading speed, sound tags, and burned-in contrastHow WCAG 1.2.x thinking maps to real files: CPS, line length, SDH-style cues, and contrast for open captions. Platform presets in the dashboard enforce readable CPS before you hand off to clients.
- Educators & classrooms — CaptionPass for instructionPartner program for instructors: API keys, workspace pilots, Learn guides, and classroom-appropriate access. Students can start with the free homepage tool before moving to dashboard projects.
- How to evidence ADA Title II captionsWhat the DOJ web rule requires for captions, what counts as evidence rather than an assurance, and what a per-asset conformance record contains. Deadlines are dated and cited, and the tense is computed so the page cannot describe a passed deadline as upcoming.
- What goes in the caption rows of a VPATWhich WCAG criteria are the caption rows of an Accessibility Conformance Report, which conformance level each evidence outcome actually supports, and why Not Evaluated beats an unjustified Not Applicable.
- The FCC's four caption quality standardsAccuracy, synchronicity, completeness and placement under 47 CFR 79.1(j)(2) — what each requires, and precisely which of them a caption file can and cannot settle.
- How to check captions against WCAG 2.1 AAWhich WCAG success criteria a caption file bears on, how to run a per-criterion check that names its own limits, and what a clean result does and does not establish.
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