How to Add Subtitles to a Video (Auto-Generated, Free)

Video without captions is video without reach. 85% of social video is watched on mute. Adding subtitles manually takes hours — AI tools do it in under a minute. Here is the fastest way.

The path everyone takes

You can use CapCut (auto captions built in, limited accuracy), Descript (paid editor), YouTube Studio (free but slow), or a dedicated transcription tool like FastTranscriber that exports clean SRT files you can drop into any editor.

Two approaches

Option A: SRT file + your video editor

Best if you want full control over font, styling, and animation.

Upload your video to the audio to SRT converter
Download the .srt file in seconds
Import the SRT into Premiere, Final Cut, CapCut, or DaVinci Resolve
Style and export

Option B: Burn captions directly

Best if you are posting to TikTok, YouTube Shorts, or Reels and want Snapchat-style text.

Run your video through FastTranscriber and export SRT
Use ffmpeg with subtitles=yourfile.srt to burn them in, or use CapCut's import SRT feature

Supported formats

MP4, MOV, WebM all work. Free tier files can be up to 1.3 GB. Pro tier allows 15 GB for full resolution source video.

Why not just use YouTube's auto captions?

YouTube's auto captions take 30+ minutes, produce lower-quality transcripts than Whisper-based tools, and can't be exported until the video is fully processed. If you need captions on the source file before uploading (for TikTok, Instagram, or an edit), you need something faster. FastTranscriber runs in under 30 seconds on a 10-minute video — see the speed test.

Tips for clean subtitles

Export at 128 kbps or higher for best accuracy
For social video (vertical), break lines every 4–5 words so text stays readable on mobile
Proofread automotive terms, proper nouns, and technical jargon — these are where AI makes mistakes

Related guides

Start free: FastTranscriber.