What's the difference between SRT and VTT?

SRT (SubRip Text) and VTT (WebVTT) are nearly identical in structure. Both list numbered cues with start/end timestamps and text. The main differences: VTT starts with a 'WEBVTT' header, uses a period (.) instead of a comma (,) as the decimal separator in timestamps, and supports optional cue settings for positioning. VTT is the standard for HTML5 video and streaming; SRT is more broadly supported in desktop players and video editors.

Can I edit the subtitle timing here?

This tool is designed for format conversion, not a full timeline editor. That said, after converting you can copy the output and paste it into any text editor to adjust timestamps manually — SRT and VTT files are plain text. For frame-accurate re-timing you'll want a dedicated subtitle editor like Aegisub or Subtitle Edit.

Does this work for ASS/SSA subtitles?

Yes — the converter parses Dialogue lines from ASS/SSA files and extracts the text and timing. Note that rich formatting (colors, positions, karaoke effects) is dropped when converting to SRT or VTT, since those formats don't support ASS's advanced styling system. If you need to preserve styles, convert ASS → ASS and only edit the timing.

Is there a file size limit?

There's no hard limit enforced by the tool — subtitle files are typically very small (a few KB to a few hundred KB at most), so even a 90-minute film's worth of captions will convert in milliseconds. If you paste an unusually large file the browser may take a moment, but it will still process it.

Are my subtitle files uploaded anywhere?

No — never. All parsing and conversion happens entirely inside your browser using JavaScript. Your file bytes never leave your device and are never sent to any server. You can verify this by watching the network tab in browser DevTools while converting.

Can I burn these subtitles into a video?

This tool handles the format conversion step — burning (also called 'hardsubbing') requires a video processing tool. For cloud burning, Lumigen can render captions directly into your video. For local use, a tool like HandBrake or a command-line encoder can bake any SRT/ASS file into the video stream.

100% free · no signup · runs in your browser

Convert SRT, VTT, and ASS subtitles
— in seconds, in your browser.

Drop a subtitle file, pick an output format, and download. We never upload your file.
Fix encoding, shift timing, strip tags, and merge cues — all client-side.

Local only Instant Unlimited

Converter

FREE

Files never leave your browser

Source

Drop a subtitle file

.srt, .vtt, .ass, .ssa, .sbv, .txt — up to 5 MB

Output

Converted output will appear here

Conversion happens entirely on your device. We don't see, store, or upload anything.

Generate captioned video with Lumigen.

You're converting captions — Lumigen generates the video with captions already burned in. Script to captioned short-form in under 5 minutes, no conversion step required.

Generate the video See how it works

Captions burned in

SRT + VTT sidecar

Multi-language

MANUAL → LUMIGEN

BEFORE / AFTER

PREVIEW

Captions auto-synced at render

What Lumigen Adds

Native Sizing

9:16, 1:1, 16:9 rendered at source resolution.

Smart Bitrate

Platform-optimised upload size, automatically.

Auto Captions

Burned-in or sidecar — your choice.

How Subtitle Converter works

Upload your subtitle file

Drop in any .srt, .vtt, .txt, or .ass file. Browser-only — your file never leaves your device.

Pick the output format

Convert between SRT, VTT, TXT, or ASS. We auto-detect the source format.

Download or use in Lumigen

Copy the converted text instantly, or sign in to keep a copy and use it in your next Lumigen video.

Features

Everything you need to create
stunning videos.

From avatars and voiceovers to captions and exports — all in one place.

AI Avatars01

Script to Video02

Voice & Music03

Captions & Export04

Tech Enthusiast

EN · JP

Outdoor Adventurer

EN · DE

Industry Consultant

ES · FR

Senior Executive

EN · ZH

Tech Enthusiast

EN · JP

50+ avatars

AI Avatars

Choose from 50+ realistic AI avatars. Each speaks naturally with perfect lip-sync, available in 30+ languages.

Get started

Everything you need

One tool. Every feature.
Zero learning curve.

CustomFun FactsHow ToProduct Review

Tell us a bit more (Optional)

Create a 60-second TikTok video about the most surprising facts about the Roman Empire, ending with a call to follow

Generating script... ↵ Generate

AI Script Generator

Write or generate your video script automatically. Pick a style and let the AI do the rest — or edit it yourself.

Charlotte

Swedish, Female

Lily

British, Female

James

American, Male

50+ Unique Voices

Pick from male and female voices across 30+ languages. Preview any voice before generating.

Realistic AI Avatars

Choose from 50+ hyper-realistic avatars with perfect lip-sync. No green screen needed.

+45 more

Select a style or pick a template

TikTok / Short / Reel YouTube Explainer Product Demo AI Face Swap Testimonial News Style

Video Styles & Templates

TikTok shorts, YouTube docs, product demos — all with dedicated templates optimized for each platform and format.

Anime

Neon

Cinematic

Pixar

Ghibli

Watercolor

26+ AI Visual Styles

From cinematic realism to anime, neon, Ghibli, and pixel art — pick a style and every scene is generated to match it.

CinematicAnimeNeonPixarGhibliRetro VHSWatercolorNoirDreamcore+17 more

ResolutionFrame Rate

720p1080p4K60fps

1920 × 1080

FormatCompression

MP4MOVWebM

High-Quality — Forever Yours

Export crisp 1080p or 4K videos. Download once and keep forever — even if you cancel.

Works with every platform you use

TikTok

YouTube

Instagram

Facebook

Export optimized for every platform

What you can create

Every video format, powered by AI.

From product demos to viral social ads — generate studio-quality videos for any use case in minutes, no editing skills required.

Product Demos

Turn features into 60-second videos that sell

TikTok Shorts

Viral-ready vertical videos that stop the scroll

YouTube Shorts

Short-form content that grows your channel fast

Social Ads

High-converting creatives for every platform

5,284 creators already publishing with Lumigen

Join the fastest-growing community of AI video creators — from solo founders to global agencies.

Output Gallery

See what you can create.

TikTok stories, YouTube docs, product demos — all generated in under 5 minutes.

Cinematic

AI Generated

Rainy Night in Tokyo

UGC Video

AI Generated

AI Avatar Product Demo

Finance

AI Generated

Why Bitcoin Is Digital Gold

Money Mindset

AI Generated

Rich Mindset Breakdown

Mixed Scenes

AI Generated

Multi-Scene Showcase

Motion Control

AI Generated

Sync & Dance Duo

More free tools

Aspect Ratio Calculator

Resize any video for TikTok, Reels, and Shorts with crop preview.

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Bitrate Calculator

Find the right bitrate for your codec, resolution, and duration.

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Script to Duration

Paste a script and see exactly how long it will run per platform.

Open tool

Safe Zone Previewer

Overlay TikTok/Reels/Shorts UI masks on your image or thumbnail.

Open tool

Start creating today

Start creating AI videos today

Join 5,284 creators already generating videos at scale.

FAQ

Convert SRT, VTT, and ASS subtitles — in seconds, in your browser.

Drop a subtitle file

Generate captioned video with Lumigen.

How Subtitle Converter works

Upload your subtitle file

Pick the output format

Download or use in Lumigen

Everything you need to createstunning videos.

AI Avatars

One tool. Every feature.Zero learning curve.

AI Script Generator

50+ Unique Voices

Realistic AI Avatars

Video Styles & Templates

26+ AI Visual Styles

High-Quality — Forever Yours

Every video format, powered by AI.

Product Demos

TikTok Shorts

YouTube Shorts

Social Ads

5,284 creators already publishing with Lumigen

See what you can create.

More free tools

Start creating AI videos today

Common questions.

What's the difference between SRT and VTT?

Can I edit the subtitle timing here?

Does this work for ASS/SSA subtitles?

Is there a file size limit?

Are my subtitle files uploaded anywhere?

Can I burn these subtitles into a video?

Convert SRT, VTT, and ASS subtitles
— in seconds, in your browser.

Everything you need to create
stunning videos.

One tool. Every feature.
Zero learning curve.