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Tool Walkthroughs April 29, 2026 6 min read by VideoToolShack Editorial

Add Subtitles Walkthrough: How to Use the Free Browser Tool

The Add Subtitles tool burns an SRT subtitle file permanently into any video — creating open captions that display on every platform, player, and device without any configuration. This walkthrough covers every step from loading your files to downloading your captioned video, plus common issues and how to avoid them.

What You’ll Need Before Starting

  • Your video file — MP4, MOV, WebM, AVI or most common formats
  • An SRT subtitle file — the .srt file containing your caption text and timestamps

If you don’t have an SRT file yet, use the free Text to SRT tool to create one from your script or transcript. See the SRT creation guide for timing best practices before proceeding.

Verify timing before burning in Once captions are burned into the video, they can’t be removed or adjusted without re-running the entire process. Always verify your SRT timing is accurate before this step — load the SRT alongside your video in VLC and check the timing throughout. Fixing a timing error in a text file takes 30 seconds; re-burning takes several minutes.

Step-by-Step: Adding Subtitles to a Video

1
Open the Add Subtitles Tool

Go to videotoolshack.com/tools/add-subtitles.php. No sign-in, no installation, no upload.

2
Load Your Video

Drop or select your video file. The video loads into the preview player. For best results, ensure the video is already trimmed to its final length — avoid trimming after captions are burned in.

3
Upload Your SRT File

Select your .srt file. The tool reads the timestamps and text. The preview shows how the captions will appear over your video so you can verify position and legibility before processing.

4
Check Caption Position

Confirm that the subtitle position clears any important content in the frame, and avoids the lower 35% if the video will be posted to Instagram or TikTok (where platform UI overlays that area). Adjust if the tool offers position options.

5
Burn In and Download

Click Add Subtitles. Processing runs locally in your browser — speed depends on video length. When complete, download your captioned video. The captions are now permanently part of the video.

Common Issues and How to Avoid Them

  • Captions are off-sync — timing error in the SRT file. Go back, fix the timestamps in a text editor, and re-run. Check that your SRT timestamps use commas (00:00:02,500) not periods.
  • Captions overlap platform UI — reposition captions higher in the frame before burning in, or adjust in your SRT file if the tool supports position tags.
  • Text too small to read — if the video is very wide or the font size is small, re-evaluate the caption style before burning. On a 1920px wide video, subtitle text needs to be at least 40–48px to be readable on mobile.
  • Wrong character encoding — if captions show garbled text or missing characters, ensure your SRT file is saved as UTF-8. Open it in a text editor and re-save as UTF-8 if needed.

After Adding Subtitles: What’s Next?

With captions burned in, the next and final step before distribution is adding your logo watermark using the Add Watermark tool. Watermark always goes last, after all content modifications including captions.

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