SRT vs VTT: subtitle format comparison and guide

SRT (SubRip Text) and VTT (WebVTT) are the two most widely used subtitle file formats: SRT is the legacy standard with near-universal video player support, while VTT is the modern web-native format designed for HTML5 video with built-in styling and positioning capabilities.

Choosing the right subtitle format affects compatibility, styling options, and how your captions render across platforms. This guide breaks down exactly how SRT and VTT differ, which platforms support each, and when to pick one over the other.

What is SRT?

SRT stands for SubRip Text, a subtitle format that originated in the late 1990s as part of the SubRip software, a tool designed to extract ("rip") subtitles from DVDs. Despite its age, SRT remains the most universally supported subtitle format in the industry.

An SRT file is a plain text file with a .srt extension. Each subtitle entry consists of three parts: a sequential numeric index, a timecode line showing start and end times, and one or more lines of subtitle text. Entries are separated by blank lines.

Here is the structure of an SRT file:

1
00:00:01,000 --> 00:00:04,000
This is the first subtitle line.

2
00:00:05,500 --> 00:00:08,200
This is the second subtitle.
It can span multiple lines.

3
00:00:10,000 --> 00:00:13,750
Speaker identification is done
manually in the text itself.

Key characteristics of the SRT format:

• Timecode format: HH:MM:SS,mmm (hours, minutes, seconds, milliseconds separated by a comma)
• Sequential numbering: Each cue is numbered starting from 1
• Plain text only: No native support for styling, colors, or positioning
• Encoding: Typically UTF-8, though older files may use other encodings
• Arrow separator: Start and end times are separated by -->

The simplicity of SRT is both its greatest strength and its main limitation. Any text editor can create and modify SRT files, and virtually every video player and editing application can read them. However, you cannot control font size, color, placement, or any other visual property within the format specification itself.

What is VTT?

VTT stands for WebVTT (Web Video Text Tracks), a subtitle and caption format developed by the W3C (World Wide Web Consortium) specifically for use with the HTML5 <video> and <track> elements. The specification was first published in 2010 and became a W3C Recommendation, making it the official standard for web-based video captions.

A VTT file is a plain text file with a .vtt extension. It must begin with the header WEBVTT, optionally followed by metadata. Each cue can include an optional identifier, a timecode line, and the subtitle text.

Here is the structure of a VTT file:

WEBVTT
Kind: captions
Language: en

intro
00:00:01.000 --> 00:00:04.000
This is the first subtitle line.

00:00:05.500 --> 00:00:08.200
This is the second subtitle.
It can span multiple lines.

styled-cue
00:00:10.000 --> 00:00:13.750 position:10% align:start
<v Speaker 1>This cue has positioning
and a voice tag for speaker ID.</v>

Key characteristics of the VTT format:

• Mandatory header: Every file must start with WEBVTT
• Timecode format: HH:MM:SS.mmm (uses a period for milliseconds, not a comma)
• Optional cue identifiers: Cues can have named IDs instead of sequential numbers
• CSS styling support: Supports ::cue pseudo-element for styling via CSS
• Positioning: Cue settings allow vertical, line, position, size, and alignment control
• Voice tags: <v Speaker Name> tags enable speaker identification within the format
• Metadata headers: Key-value pairs after the WEBVTT header for additional context
• Comments: Supports NOTE blocks for file-level annotations

VTT was designed to address the limitations of older subtitle formats while integrating natively with web technologies. Its support for CSS styling, speaker voice tags, and cue positioning makes it significantly more expressive than SRT for web-based video players.

SRT vs VTT: key differences

While SRT and VTT look similar at first glance, they differ in several important ways beyond the file extension.

Feature	SRT	VTT
File extension	.srt	.vtt
File header	None required	WEBVTT required
Timecode separator	Comma (,)	Period (.)
Cue numbering	Sequential numbers required	Optional named identifiers
Text styling	Not supported	CSS ::cue styling, bold, italic, underline
Positioning	Not supported	Line, position, size, alignment settings
Speaker identification	Manual (text-based)	Native voice tags (<v>)
Comments	Not supported	NOTE blocks supported
Metadata	Not supported	Header metadata key-value pairs
HTML tags	Limited (some players support <b>, <i>)	Full support (<b>, <i>, <u>, <c>, <v>, <lang>)
Character encoding	Varies (UTF-8 recommended)	UTF-8 required
Web standard	No	W3C Recommendation

The most practical difference for most users is compatibility versus capability. SRT works everywhere but does nothing beyond displaying timed text. VTT works natively on the web with rich formatting options but has narrower support in desktop video editors and legacy media players.

Platform compatibility

Knowing which platforms accept which format saves time and avoids conversion headaches. Here is a breakdown of support across major platforms and tools.

Platform / tool	SRT	VTT	Notes
YouTube	Yes	Yes	Accepts both for manual upload; auto-generates SRT
Vimeo	Yes	Yes	Accepts both; recommends VTT for styling
HTML5 <video>	No	Yes	VTT is the only natively supported format
VLC Media Player	Yes	Yes	Full support for both formats
Adobe Premiere Pro	Yes	No	SRT import/export; no native VTT support
DaVinci Resolve	Yes	No	SRT preferred for import
Final Cut Pro	Yes	No	SRT and iTT supported
Facebook / Instagram	Yes	Yes	SRT preferred for upload
TikTok	Yes	No	SRT for closed caption upload
Netflix	Both (via TTML)	Both (via TTML)	Prefers TTML/DFXP for delivery
Zoom	Yes	Yes	VTT for cloud recordings
Microsoft Teams	Yes	Yes	VTT generated for meeting transcripts
WordPress	No	Yes	HTML5 video uses VTT natively
Wistia	Yes	Yes	Accepts both for caption upload

The general pattern: web platforms and modern tools support VTT, while video editing software and legacy players favor SRT. If you are producing content for web playback, VTT is the natural choice. If you are delivering files to editors or uploading to social media, SRT is the safer bet.

When to use SRT

Choose SRT when broad compatibility matters more than formatting control.

Video editing workflows. Most professional editing software -- Premiere Pro, DaVinci Resolve, Final Cut Pro, Avid Media Composer -- handles SRT natively. If your subtitle files need to move between editors, SRT avoids conversion issues.

Social media uploads. Platforms like TikTok and Instagram accept SRT for burned-in or closed captions. When uploading captions to social platforms, SRT is often the only accepted format.

Legacy system support. Older media players, set-top boxes, and DVD/Blu-ray authoring tools were built around SRT. If your audience uses older playback hardware or software, SRT guarantees compatibility.

Simplicity and portability. SRT files are trivially easy to create, edit, and debug. There is no header to remember, no special syntax, and the format is self-explanatory even to someone seeing it for the first time.

Freelance and client delivery. When delivering subtitle files to clients or collaborators, SRT is the safest default because it requires no explanation and works with whatever tool the recipient uses.

When to use VTT

Choose VTT when you need web-native features, styling, or accessibility compliance.

HTML5 web video. If you are embedding video on a website using the <video> element, VTT is the only subtitle format supported by the <track> tag. No conversion layer or JavaScript library is needed.

Styled subtitles. VTT lets you apply CSS styling to captions using the ::cue pseudo-element. You can control font, color, background, opacity, and text shadow -- all through standard CSS.

video::cue {
  background-color: rgba(0, 0, 0, 0.7);
  color: #ffffff;
  font-size: 1.2em;
}

Caption positioning. VTT supports cue settings for precise placement. This is useful for avoiding on-screen graphics, speaker names, or lower-third overlays.

00:00:10.000 --> 00:00:14.000 position:10% line:0 align:start
This caption appears at the top-left.

Speaker identification. VTT's voice tags (<v>) provide a structured way to identify speakers, which is useful for meeting transcripts, interviews, and multi-speaker content. Players can use these tags to style different speakers with different colors.

Accessibility compliance. For WCAG 2.1 compliance on web content, VTT is the recommended format because it integrates with HTML5 accessibility APIs and supports both captions (for deaf/hard-of-hearing viewers) and descriptions (for blind/low-vision viewers).

How to convert between SRT and VTT

Converting between SRT and VTT is straightforward because the formats are structurally similar.

SRT to VTT conversion

To convert an SRT file to VTT manually:

1. Add WEBVTT as the first line of the file
2. Add a blank line after the header
3. Replace all commas in timecodes with periods (00:00:01,000 becomes 00:00:01.000)
4. Optionally remove the sequential cue numbers (they are not required in VTT)
5. Save the file with a .vtt extension

Before (SRT):

1
00:00:01,000 --> 00:00:04,000
Welcome to the presentation.

2
00:00:05,500 --> 00:00:08,200
Today we will cover three topics.

After (VTT):

WEBVTT

00:00:01.000 --> 00:00:04.000
Welcome to the presentation.

00:00:05.500 --> 00:00:08.200
Today we will cover three topics.

VTT to SRT conversion

To convert a VTT file to SRT:

1. Remove the WEBVTT header and any metadata lines
2. Replace all periods in timecodes with commas (00:00:01.000 becomes 00:00:01,000)
3. Add sequential cue numbers before each timecode line
4. Remove any VTT-specific features (voice tags, positioning, CSS classes)
5. Save the file with a .srt extension

Automated conversion

For batch conversions or frequent format switching, tools like Vocova handle this automatically. When you generate subtitles from audio or video in Vocova, you can export directly to both SRT and VTT (along with PDF, DOCX, CSV, and TXT) without manual conversion. This is particularly useful when you need the same content in multiple formats for different platforms.

Most video editing applications and online subtitle editors also include built-in format conversion. FFmpeg can convert between formats on the command line:

ffmpeg -i subtitles.srt subtitles.vtt

Other subtitle formats to know

SRT and VTT cover the majority of use cases, but several other formats exist for specialized applications.

ASS / SSA (Advanced SubStation Alpha)

ASS and its predecessor SSA are subtitle formats popular in the anime fansubbing community. They support advanced styling including fonts, colors, animations, karaoke effects, and precise on-screen positioning. ASS files are significantly more complex than SRT or VTT and are primarily used with media players like VLC and MPC-HC. Most web platforms do not accept ASS files directly.

TTML (Timed Text Markup Language)

TTML is an XML-based subtitle format maintained by the W3C. It is used in professional broadcast and streaming workflows, particularly by Netflix, BBC, and other major content distributors. TTML supports rich styling, region-based positioning, and multiple subtitle tracks in a single file. Its XML structure makes it verbose but highly structured.

SCC (Scenarist Closed Captions)

SCC is a legacy format used in North American broadcast television. It encodes CEA-608 closed caption data and is required for FCC-compliant captioning in the United States. SCC files are not human-readable and require specialized software to create and edit. If you are producing content for broadcast TV, your captioning vendor will likely deliver SCC files.

SBV (SubViewer)

SBV is a simple subtitle format historically used by YouTube for auto-generated captions. It is structurally similar to SRT but uses a different timecode format. SBV has largely been superseded by SRT and VTT for YouTube uploads.

Frequently asked questions

Can I upload SRT files to YouTube?

Yes. YouTube accepts both SRT and VTT files for manual subtitle uploads. You can upload them through YouTube Studio under the "Subtitles" section of any video. YouTube also auto-generates captions, which can be downloaded in SRT format.

Does VTT support styling and colors?

Yes. VTT supports CSS styling through the ::cue pseudo-element, inline tags like <b>, <i>, and <u>, and class-based styling with <c.classname>. You can control font color, background color, text size, and opacity. However, not all video players render VTT styles -- support depends on the player implementation.

Which format is better for accessibility?

VTT is the recommended format for web accessibility compliance. It integrates with HTML5 accessibility APIs, supports kind attributes (captions, descriptions, chapters), and allows speaker identification via voice tags. For WCAG 2.1 compliance on web video, VTT with the <track> element is the standard approach.

Can SRT files contain formatting like bold or italic?

The SRT specification does not include formatting. However, many video players interpret basic HTML tags (<b>, <i>, <u>) within SRT cues and render them accordingly. This behavior is not guaranteed across all players, so relying on it for critical formatting is risky.

What is the maximum file size for subtitle files?

There is no format-level file size limit for either SRT or VTT. Platform-specific limits vary: YouTube allows subtitle files up to 10 MB, while most platforms accept files well under 1 MB for typical video lengths. A one-hour video typically produces a subtitle file between 50-150 KB.

How do I generate SRT or VTT files from audio or video?

You can generate subtitle files by transcribing your audio or video with an automatic speech recognition tool. Services like Vocova transcribe audio in over 100 languages with timestamps and speaker labels, then let you export directly to SRT, VTT, and other formats. For a comparison of subtitle generation tools, see our guide to the best AI subtitle generators.