Skip to content
WEBVTT · Validation · STYLE block

Subtitles a player will accept

A subtitle file is code. One missing blank line, one comma where a dot belongs, and the player silently shows nothing at all. This editor parses what you paste, checks what actually breaks playback, and writes a file that starts with WEBVTT — because that first line is not optional.

Short answerLast edited October 31, 2026

The VTT Subtitle Generator builds or repairs a WebVTT or SRT caption file. It shifts all timings by a fixed amount, fits the cues to a target duration, and checks the characters per line, reading speed and minimum gap before you save. The result can be previewed before download.

How it works

1

Open your subtitles

Paste an SRT or WebVTT file, or open one from your device.

2

Fix the timing and the lines

Shift every cue, limit the characters per line and set the reading speed.

3

Download the .vtt file

Save the cleaned WebVTT file for the player or platform.

Cue sheetall clean
  • 100:00:01.000→00:00:04.500Paste your subtitle file aboveok
  • 200:00:04.800→00:00:09.200Each cue is checked against the limitsok
  • 300:00:09.400→00:00:11.100Overlaps and short cues are flaggedok
  • 400:00:11.300→00:00:16.000Export VTT, SRT or plain textok
subtitles.vttwhat the player reads
WEBVTT

1
00:00:01.000 --> 00:00:04.500
Paste your subtitle file above

2
00:00:04.800 --> 00:00:09.200
Each cue is checked against the limits

3
00:00:09.400 --> 00:00:11.100
Overlaps and short cues are flagged

4
00:00:11.300 --> 00:00:16.000
Export VTT, SRT or plain text

What gets checked

Overlaps

Two cues on screen at once is legal in VTT and wrong in practice. The fix button pushes the second cue behind the first with a small gap.

Reading speed

Characters per second is the honest measure of readability. Anything above 21 CPS is flagged, and the line is what needs shortening.

Line length

Text wider than the safe area is cut off on phones. Lines are wrapped at 32, 42 or 50 characters, at word boundaries.

Cue duration

Under 0.6 seconds a cue flashes; over 7 seconds it lingers. Both are reported so you can decide which one to fix.

The limits, written down

RuleCommon valueWhy
Characters per line42 (32 for vertical video)Fits the safe area on a phone
Lines per cue2Three lines cover the picture
Characters per second17–21The speed an average viewer reads comfortably
Minimum duration0.6–1 sShorter reads as a flash
Gap between cues2 framesPrevents the text from appearing to stutter
Timestamp separatorA dot in VTT, a comma in SRTThe single most common reason a file is ignored
WebVTT and SRT: what actually differs?

VTT starts with the line WEBVTT, uses a dot before the milliseconds and supports cue settings such as line:90% and align:center after the timestamp. SRT has none of that: it is a number, two timestamps with commas and the text. VTT also allows a STYLE block that styles every cue through the player, and NOTE blocks for comments.

Where do the STYLE rules apply?

Only in players that implement them — browsers do, most desktop players do not. The styling written here uses ::cue, which is the standard selector, so the file stays valid even where the rules are ignored. The text itself always remains readable.

Why does my file show nothing?

The usual causes, in order: the file does not start with WEBVTT; a timestamp uses a comma; a cue has no blank line before it; the encoding is not UTF-8. All four are fixed by parsing the file here and exporting it again.

Can I convert VTT back to SRT?

Yes — the SRT button writes the same cues with commas and cue numbers, dropping the STYLE block and cue settings, because SRT cannot carry them.

Publishing checklist
  • File starts with WEBVTT on its own line
  • Timestamps use a dot, not a comma
  • No cue overlaps the next one
  • Every line fits 42 characters
  • Reading speed stays under 21 CPS
  • Saved as UTF-8 without a BOM

VTT questions

Is this tool free and private?
Yes. Parsing, validation and export happen in the browser. No file is uploaded, no account is needed and no watermark is added to anything.
Can I edit an existing VTT file?
Open it with the file button or paste its contents. Every cue becomes an editable row with its own start and end field, and the code preview updates as you type.
Does it handle SRT input?
Yes, and it handles SRT with commas, VTT with dots, cue identifiers, NOTE blocks and styling tags. Anything it cannot read is skipped instead of breaking the file.
Which format should I upload to YouTube?
YouTube accepts SRT, VTT and SBV. SRT is the safest for uploads, VTT for a web player. Export whichever your destination asks for — both come from the same cues.
How do I shift subtitles for a different cut?
Use the shift slider for a constant offset (a new intro of 4 seconds means +4000 ms) or the fit slider to stretch everything to a new total length. Both change every cue at once.

WebVTT, Explained Without the Specification

WebVTT is the subtitle format of the open web. It was designed to be readable by humans and strict enough for machines, and it is smaller than it looks: a signature line, a series of cues, and optional blocks for styling and comments.

The anatomy of a file

It begins with WEBVTT on a line of its own. Then come cues, separated by a blank line. Each cue may have an identifier, then a timing line, then the text. The timing line looks like 00:00:04.500 --> 00:00:07.200 and may continue with settings such as align:start or line:85%.

That is the entire format. Everything else — STYLE blocks, NOTE blocks, regions — is optional decoration around it.

The mistakes that break playback

By far the most common is a comma instead of a dot in the milliseconds. That is SRT syntax leaking into a VTT file, and players reject the whole cue, sometimes the whole file. The second is a missing blank line between cues, which merges two cues into one unparseable block. The third is a byte order mark at the start of the file: invisible, and enough to stop a strict parser before the signature line.

Encoding matters too. UTF-8 is required for anything outside ASCII, and without it accented characters arrive as question marks.

Reading speed is the real quality bar

A cue can be perfectly timed and still useless. Characters per second tells you whether the eye can keep up: under 17 is comfortable, 21 is the usual ceiling for broadcast, and above 25 the viewer stops reading and starts guessing.

The fix is rarely to make the cue longer. It is to shorten the text: drop the filler, split the sentence across two cues, or let the picture carry the meaning for a moment.

Styling that survives

A STYLE block with a ::cue rule sets colour, size and background inside browsers. Most desktop players ignore it entirely, and that is fine — the text stays readable because the styling is decoration, not structure. Never hide information in a style rule: assume someone will see the file without it.

One file, many places

Keep the cues clean and the exports become trivial: VTT for the web player, SRT for the video platform, plain text for the transcript page. The captions generator on this site produces the first draft; this studio is where the file becomes something a player will actually accept.

Where to go next

Video to Audio ExtractorSave the sound of MP4, MOV and WebM videos as MP3 right in your browser.No uploadFreeOpen tool Audio Format ConverterBatch convert between MP3, WAV, M4A, FLAC, OGG and OPUS.No uploadFreeOpen tool MP3 Cutter & Ringtone StudioTrim any part of a song, add fades and make a ringtone.No uploadFreeOpen tool Audio MergerCombine several audio files into one track with smooth transitions.No uploadFreeOpen tool Audio Loudness BoosterMake quiet recordings louder and normalize them to a standard level.No uploadFreeOpen tool Slowed + Reverb StudioCreate slowed + reverb, sped up and nightcore versions of songs.No uploadFreeOpen tool Background Noise RemoverClean hum, fan and traffic noise from voice recordings.No uploadFreeOpen tool Pitch ShifterRaise or lower the pitch by up to an octave and keep the running time exactly as it was.No uploadFreeOpen tool Silence RemoverCut the dead air out of interviews, lectures and voice notes and see how much shorter the file gets.No uploadFreeOpen tool Audio EqualizerCut mud, lift speech and add air with a 10-band equalizer and six presets.No uploadFreeOpen tool Audio Reverb EffectAdd room, studio, hall or plate space with control over decay and wet mix.No uploadFreeOpen tool Audio Chorus EffectDouble a take with two or three drifting voices and stereo width.No uploadFreeOpen tool Audio Fade In/OutWrite smooth fade ins and fade outs of any length into the file itself.No uploadFreeOpen tool Stereo to Mono ConverterFold stereo to mono, keep one channel or swap left and right.No uploadFreeOpen tool Audio NormalizerEven out volume with peak or average normalization and a no-clip safety.No uploadFreeOpen tool Video Caption MakerCreate captions with AI or use an SRT file and burn them into the video.No uploadFreeOpen tool Video to Text ConverterTurn the speech of videos and recordings into text and SRT subtitles.No uploadFreeOpen tool AI Video Summary GeneratorGet the summary, chapters and notes of long videos, lectures and podcasts.AIFreeOpen tool Video Size ReducerShrink a video to the size you need for Discord, email or WhatsApp.No uploadFreeOpen tool GIF Maker & Video CutterCut part of a video and save it as a GIF or a shorter MP4.No uploadFreeOpen tool Vertical Video ConverterTurn 16:9 videos into 9:16 vertical format with a blurred background.No uploadFreeOpen tool Video Frame ExtractorSave any frame of a video as a full-resolution image.No uploadFreeOpen tool Video Metadata ViewerSee the resolution, bitrate, codec and FPS of a video file.No uploadFreeOpen tool AI Clip MakerAI finds the best moments of a long video and turns them into captioned vertical clips.AIFreeOpen tool AI Video EnhancerEnhance video quality, upscale resolution and reduce noise with AI.AIFreeOpen tool Auto Captions GeneratorGenerate accurate captions and subtitles for videos automatically.AIFreeOpen tool Smart Video TrimmerTrim videos with frame-accurate precision in your browser.No uploadFreeOpen tool Video Loop MakerCreate seamless looping videos for GIFs and social media.No uploadFreeOpen tool VTT Subtitle GeneratorGenerate WebVTT subtitle files from video transcripts.No uploadFreeOpen tool Video CropperCrop videos to focus on important areas or change aspect ratio.No uploadFreeOpen tool Image Format ConverterConvert between JPG, PNG and WebP and shrink the file with a quality slider.No uploadFreeOpen tool Social Image ResizerFit photos to Instagram, YouTube, TikTok and X sizes in one click.No uploadFreeOpen tool HEIC Photo ConverterBatch convert iPhone HEIC photos to JPG or PNG.No uploadFreeOpen tool EXIF & GPS RemoverDelete the GPS location and camera data of a photo before you share it.No uploadFreeOpen tool Watermark MakerAdd your @handle or logo to photos and videos.No uploadFreeOpen tool Instagram Grid & Carousel MakerSplit a wide photo into a seamless carousel or a profile grid.No uploadFreeOpen tool AI Video Idea FinderTen filmable video ideas with a hook and a reason, plus three series concepts.AIFreeOpen tool AI Title & Tag WriterWrite titles, descriptions and tags for YouTube, TikTok, Reels and more.AIFreeOpen tool AI Caption & Bio WriterCaptions, hashtag sets and bios that fit every platform limit.AIFreeOpen tool AI Hook & Script WriterHooks that grab viewers in the first second and timed shooting scripts.AIFreeOpen tool AI Channel Name IdeasMemorable name ideas for Instagram, TikTok, YouTube, X and Twitch.AIFreeOpen tool AI Meta Description GeneratorWrite title tags and meta descriptions that fit Google and earn the click.AIFreeOpen tool AI Product Description WriterTurn a spec sheet into three product descriptions, benefit bullets and search phrases.AIFreeOpen tool AI Blog Outline GeneratorPlan an article that answers the search: headlines, headings, word budget, FAQ and internal links.AIFreeOpen tool AI Podcast Show Notes GeneratorTurn an episode transcript into a summary, six takeaways, chapters, quotes, titles and tags.AIFreeOpen tool AI Text RewriterRewrite a text shorter, simpler, more formal or more persuasive, and see exactly what changed.AIFreeOpen tool AI TranslatorTranslate between seven languages and keep the register: formal, neutral or informal.AIFreeOpen tool AI FAQ GeneratorWrite the questions customers actually ask, with answers, follow-ups and FAQ schema for the page.AIFreeOpen tool AI Storyboard GeneratorTurn an idea into a timed shot list you can film alone: framing, action, on-screen text and voiceover.AIFreeOpen tool Social Keyword FinderFind the phrases and questions people search inside Instagram, TikTok, YouTube and Pinterest.AIFreeOpen tool Image CompressorShrink photos to a target size for a form, an email or a shop page, without leaving the browser.No uploadFreeOpen tool Favicon & App Icon GeneratorMake every icon a site needs: 16 to 512 pixels, a real favicon.ico and the HTML to paste.No uploadFreeOpen tool Image CropperCrop a photo to a social size, a cover or a profile picture by dragging the frame.No uploadFreeOpen tool Image to PDFTurn photos and scans into one PDF: page size, orientation, margin and page order.No uploadFreeOpen tool Passport & ID Photo MakerCrop a photo to passport, visa or ID sizes with a head-height guide and print it on one sheet.No uploadFreeOpen tool Meme GeneratorPut a caption on any picture: four layouts, outlined type and a square export for every feed.No uploadFreeOpen tool AI Background RemoverRemove backgrounds from images instantly with AI.AIFreeOpen tool AI Image UpscalerUpscale images up to 4x while enhancing details with AI.AIFreeOpen tool AI Object RemoverErase unwanted objects, people or text from photos.AIFreeOpen tool AI Image GeneratorCreate stunning AI images from text prompts in seconds.AIFreeOpen tool AI Avatar GeneratorGenerate unique AI avatars from photos or text descriptions.AIFreeOpen tool AI Logo GeneratorGenerate a logo mark from a description and set your brand name in type, ready for a PNG.AIFreeOpen tool Image to Text OCRExtract text from images and scanned documents with high accuracy.AIFreeOpen tool Color Palette ExtractorExtract color palettes from any image automatically.No uploadFreeOpen tool Face Blur ToolAutomatically blur faces in photos for privacy protection.No uploadFreeOpen tool WebP Image ConverterConvert images to and from WebP format for better web performance.No uploadFreeOpen tool Image to Video MakerTurn photos into a slideshow video with pan, zoom and crossfades.No uploadFreeOpen tool AI Blog WriterGenerate complete blog posts with SEO optimization in seconds.AIFreeOpen tool AI Article GeneratorCreate high-quality articles on any topic with AI assistance.AIFreeOpen tool AI Email WriterWrite professional emails for any purpose instantly.AIFreeOpen tool AI Ad Copy GeneratorGenerate compelling ad copy for Google, Facebook, and more.AIFreeOpen tool AI Product Review GeneratorCreate authentic product reviews for any item.AIFreeOpen tool AI SEO Content WriterWrite SEO-optimized content that ranks higher on search engines.AIFreeOpen tool AI ParaphraserRephrase text while maintaining meaning and tone.AIFreeOpen tool AI Grammar CheckerFix grammar, spelling, and punctuation errors instantly.AIFreeOpen tool AI Resume BuilderCreate professional resumes tailored to any job.AIFreeOpen tool AI Cover Letter WriterWrite personalized cover letters for job applications.AIFreeOpen tool AI Business Name GeneratorFind the perfect name for your business or brand.AIFreeOpen tool AI Slogan GeneratorCreate catchy slogans and taglines for your brand.AIFreeOpen tool AI Hashtag GeneratorGenerate trending hashtags for social media posts.AIFreeOpen tool AI Question GeneratorCreate quiz questions and study materials with AI.AIFreeOpen tool AI Testimonial GeneratorGenerate authentic customer testimonials for your business.AIFreeOpen tool AI Press Release GeneratorWrite professional press releases in minutes.AIFreeOpen tool AI LinkedIn Post GeneratorCreate engaging LinkedIn posts that drive engagement.AIFreeOpen tool AI Twitter Thread GeneratorTurn ideas into viral Twitter/X threads.AIFreeOpen tool AI Poem GeneratorGenerate beautiful poems for any occasion.AIFreeOpen tool PDF MergerCombine several PDFs into one file, in the order you choose.No uploadFreeOpen tool PDF SplitterExtract page ranges from a PDF or save every page as its own file.No uploadFreeOpen tool PDF CompressorMake a heavy PDF small enough to send, without uploading it.No uploadFreeOpen tool PDF to Image ConverterSave every page of a PDF as a JPG or PNG at screen, print or 300 dpi quality.No uploadFreeOpen tool PDF Page OrganizerRotate, delete and reorder the pages of a PDF, then save one clean new file.No uploadFreeOpen tool Sign a PDFDraw or upload your signature, place it on the page and download the signed PDF.No uploadFreeOpen tool Unlock PDFRemove password protection from PDF files.No uploadFreeOpen tool Protect PDFAdd password protection to PDF files.No uploadFreeOpen tool Rotate PDF PagesRotate PDF pages individually or all at once.No uploadFreeOpen tool BMI CalculatorCalculate Body Mass Index and healthy weight range.No uploadFreeOpen tool Calorie CalculatorCalculate daily calorie needs based on age, weight, and activity.No uploadFreeOpen tool Loan CalculatorCalculate loan payments, interest, and amortization.No uploadFreeOpen tool Mortgage CalculatorCalculate mortgage payments and total interest.No uploadFreeOpen tool Percentage CalculatorCalculate percentages, increases, and decreases easily.No uploadFreeOpen tool Age CalculatorCalculate exact age in years, months, and days.No uploadFreeOpen tool Unit ConverterConvert between length, weight, temperature, and more.No uploadFreeOpen tool Tip CalculatorCalculate tips and split bills easily.No uploadFreeOpen tool Discount CalculatorCalculate discounts, sale prices, and savings.No uploadFreeOpen tool BMR CalculatorCalculate Basal Metabolic Rate and TDEE.No uploadFreeOpen tool Video Bitrate CalculatorTurn a target file size and a running time into the bitrate to export with.No uploadFreeOpen tool Video Size & Upload TimeSee how big a video will be, which apps accept it and how long the upload takes.No uploadFreeOpen tool Aspect Ratio CalculatorConvert 16:9, 9:16, 4:5 and any custom ratio into exact pixel sizes.No uploadFreeOpen tool Cool Text GeneratorBold, italic, script and 20+ text styles to copy into bios and captions.No uploadFreeOpen tool Social Character CounterCount characters, hashtags and emojis against every platform limit.No uploadFreeOpen tool Creator Earnings CalculatorEstimate ad and sponsorship income on YouTube, TikTok and Instagram.No uploadFreeOpen tool Sponsorship Rate CalculatorTurn followers, views, engagement and niche into a price range to quote a brand.No uploadFreeOpen tool Engagement Rate CheckerCalculate your engagement rate and compare it with typical rates.No uploadFreeOpen tool YouTube Thumbnail TesterSee how your thumbnail and title look on the YouTube home page and on phones.No uploadFreeOpen tool Vertical Video Safe Zone CheckerCheck that text and faces are not hidden under the app buttons.No uploadFreeOpen tool CTR CalculatorCalculate click-through rates and optimize campaigns.No uploadFreeOpen tool CPM CalculatorCalculate cost per mille and campaign costs.No uploadFreeOpen tool CPC CalculatorCalculate cost per click for advertising campaigns.No uploadFreeOpen tool ROI CalculatorCalculate return on investment for campaigns.No uploadFreeOpen tool RPM CalculatorCalculate revenue per mille for content monetization.No uploadFreeOpen tool Hashtag Performance CalculatorAnalyze hashtag performance and reach potential.No uploadFreeOpen tool Best Posting Time CalculatorFind optimal posting times for maximum engagement.No uploadFreeOpen tool Influencer Value CalculatorCalculate your influencer marketing value.No uploadFreeOpen tool Content Value CalculatorEstimate the monetary value of your content.No uploadFreeOpen tool Collaboration Rate CalculatorCalculate fair rates for brand collaborations.No uploadFreeOpen tool

Quick facts

  1. WebVTT separates the milliseconds with a dot (00:00:01.000) and SRT with a comma (00:00:01,000), the one difference that breaks a file when it is simply renamed.
  2. About 15 to 17 characters per second is comfortable for most viewers, so a long cue has to be split rather than shortened in time.
  3. WebVTT is the format the HTML video element reads for captions, and it separates the millisecond with a dot.W3C
  4. The older SRT format has no formal standard; it survives because every player imports it.W3C
  5. A single emoji can be several code points joined together, so “count the characters” gives a different number from “count what you see”.Unicode Consortium

Questions people ask

What is the difference between VTT and SRT?
Both are plain-text caption formats with timestamps. WebVTT is the web standard, starts with a WEBVTT header and uses a dot for milliseconds. SRT has no header and uses a comma. Most players accept both, but a file renamed from one to the other will not load.
How do I shift subtitles that are out of sync?
Apply one offset to every cue. A subtitle that appears one second too late needs a minus one second shift, and a file that is consistently early needs a positive shift. Preview a few cues in the video before saving the full file.
How do I validate a WebVTT file?
Check the WEBVTT header on the first line, the timestamp format, the order of the cues and that no cue overlaps the next. The generator checks these and reports any line that will not parse, so you can fix it before upload.

What this page is about

  • WebVTT

    The W3C subtitle and caption format used by the HTML video element, with cue timings written as 00:00:01.000.

  • Unicode

    The standard that gives every character of every script a code point, and defines what counts as one user-perceived character.

Official sources cited on this page

  1. WebVTT: The Web Video Text Tracks FormatW3C
  2. The Unicode StandardUnicode Consortium

Continue with the same file

Each of these opens what the tool above produces. Use “Use in another tool” under the result to carry the file over — it moves from tab to tab inside your browser, never to a server.

AI Image GeneratorText → ImageTextAIFreeAI Avatar GeneratorText / Image → ImageTextAIFreeAI Logo GeneratorText → ImageTextAIFree

Switched-off tools are not listed here: only what works right now.

How would you rate VTT Subtitle Generator?Be the first to rate it