EPUB vs VTT
A detailed comparison of EPUB eBook and WebVTT Subtitle — file size, quality, compatibility, and which format to choose for your workflow.
EPUB eBook
eBooksEPUB is the open standard for reflowable digital books. It adapts text to any screen size and is supported by most e-readers except Kindle. EPUB 3 adds support for multimedia and interactivity.
About EPUB filesWebVTT Subtitle
Documents & TextWebVTT (Web Video Text Tracks) is the standard subtitle format for HTML5 video.
About VTT filesStrengths Comparison
EPUB Strengths
- Open standard — no vendor lock-in, no DRM required.
- Reflowable text — adapts to any screen size, font size, or orientation.
- Rich typography via CSS, embedded fonts, and SVG.
- Accessibility-first: native support for screen readers, adjustable text, and alt-text.
- Universal across every non-Kindle ebook reader and library app.
VTT Strengths
- Native HTML5 <video> support — no JavaScript needed.
- CSS styling, positioning, and layout control.
- Strict UTF-8 eliminates encoding guesswork.
- Supports chapters, metadata tracks, and descriptions for accessibility.
- W3C standardized — long-term stability guaranteed.
Limitations
EPUB Limitations
- Kindle does not support EPUB natively (Amazon wants you to convert to AZW3).
- Fixed-layout EPUBs (for children's books, comics) are awkward to author.
- Rendering quality varies between apps — some CSS works everywhere, some does not.
- Adobe DRM (ADEPT) or Apple FairPlay are optional layers that complicate portability.
VTT Limitations
- Slightly more verbose than SRT.
- Tooling in desktop players lags behind SRT.
- Browser CSS styling of cues varies in subtle ways.
- Conversion from SRT is easy but not always clean for edge cases.
Technical Specifications
| Specification | EPUB | VTT |
|---|---|---|
| MIME type | application/epub+zip | text/vtt |
| Extension | .epub | .vtt |
| Container | ZIP archive | — |
| Markup | XHTML 1.1 (EPUB 2); HTML5 (EPUB 3) | — |
| Standards | IDPF/W3C EPUB 2.0.1, 3.0, 3.2, 3.3 | — |
| Standard | — | W3C WebVTT Recommendation |
| Timecode format | — | HH:MM:SS.mmm --> HH:MM:SS.mmm |
| Encoding | — | UTF-8 (required, no BOM) |
Typical File Sizes
EPUB
- Novel (300 pages, text only) 200-800 KB
- Illustrated reference book 5-30 MB
- Fixed-layout children's book 30-100 MB
VTT
- 1-hour TV episode 40-100 KB
- 2-hour movie with styled cues 80-200 KB
Ready to convert?
Convert between EPUB and VTT online, free, and without installing anything. Encrypted upload, automatic deletion after 60 minutes.
Frequently Asked Questions
EPUB (Electronic Publication) is the open standard eBook format maintained by the W3C. It supports reflowable text that adapts to screen size, embedded fonts, images, and interactive content, making it the most widely supported eBook format globally.
EPUB (Electronic Publication) is the abrir padrão eBook formato maintained pelo W3C. It suporta reflowable text that adapts to screen size, embedded fonts, images, e interactive content, making it the most widely suportado eBook formato globally.
EPUB files open in Apple Books, Google Play Books, Calibre (free), Kobo eReaders, and Adobe Digital Editions. Note that Amazon Kindle does not natively support EPUB, so conversion to MOBI or AZW3 is needed.
EPUB arquivos abrir in Apple Books, Google reproduzir Books, Calibre (free), Kobo eReaders, e Adobe Digital Editions. Note that Amazon Kindle does not natively support EPUB, so conversion to MOBI ou AZW3 is needed.
Use EPUB for reading on phones and eReaders since it reflows text to fit any screen. Use PDF for documents with fixed layouts like textbooks with precise formatting, scanned pages, or documents intended for printing.
Use EPUB para reading on phones e eReaders since it reflows text to fit any screen. usar PDF para documents com fixed layouts like textbooks com precise formatoting, scanned pages, ou documents intended para printing.