How to add subtitles to a video (automatic captions, SRT or burned in)

Updated 2026-11-05

A large share of people scroll through video with the sound off, and a clip without captions is easy to skip. Captions also help viewers who are deaf or hard of hearing, people watching in a second language, and anyone in a noisy place. Here is how to add them without typing every word yourself.

Burned-in captions or a separate SRT file?

Burned-in (open) captions are drawn into the picture itself. They show up everywhere — Instagram, TikTok, a group chat, a presentation — and look exactly as you styled them, but viewers can't turn them off and you can't edit them after export.

An SRT file is a small text file with numbered lines and timestamps. YouTube, Vimeo and most video players load it as a subtitle track the viewer can switch on or off, and search engines can read it. Use SRT for YouTube and long videos; burn captions in for short social clips, where many apps ignore subtitle files.

Generate captions automatically

In the Localvert video editor, drop in your video, open the Captions tab and press Auto-generate captions. The Whisper speech-recognition model listens to the edited timeline and creates timed caption blocks. Pick the spoken language if you know it — auto-detection works, but choosing it avoids mistakes on short clips.

The Fast model (about 40 MB) is fine for clear speech; Accurate (about 77 MB) handles accents, names and background noise better. The model downloads once and then runs on your own device, so the audio of your video is never sent to a server.

Fix the words and the timing

Automatic captions are a first draft. Play the video and read along: names, numbers and technical terms are the usual mistakes. Click a caption in the list to jump to it and correct the text. On the timeline, drag a caption block to move it and drag its right edge to make it stay longer.

Speech recognition sometimes invents a line such as "Thank you." over music or silence. Localvert drops lines like that when the audio is nearly silent, but check the parts of your video that have no talking.

Make captions readable on a phone

Keep each caption to one or two short lines — roughly 35 to 42 characters per line — and leave it on screen for at least a second. Split long sentences at natural pauses rather than in the middle of a phrase.

Use a large bold font and strong contrast: white text with a dark box behind it is readable over any background. For vertical videos, keep captions above the bottom fifth of the frame, where apps place their own buttons and descriptions; the center or slightly lower is safest.

Export

Tick "Burn captions into the video" and export an MP4, or untick it and press Download SRT to get the subtitle file on its own. You can do both: burn them into a short clip for social media and upload the SRT alongside the full version on YouTube.