Guide
How to add auto captions to a video
The shortest useful workflow: get timed captions, fix the words that matter, style them for the feed, and export a file you can post.
Last updated: 31 October 2026
TL;DR: Drop the finished clip into AutoCaptions, generate captions, spend the review time on names and the first ten seconds, then choose 9:16 or 16:9 and export a captioned MP4. If the platform accepts subtitle files, download SRT/VTT instead.
Before you start
- Finish the edit first. If you trim after captioning, the timing will drift.
- Know the destination: vertical feed, YouTube, course player, or a client deliverable.
- Have the correct spellings of names, brands and technical terms ready.
Step 1 — Drop the video
Open the auto caption generator and choose your file. MP4, MOV, WebM and MKV are the common formats. The browser extracts the audio track; the video itself is not uploaded as a caption project.
Step 2 — Review the transcript
Do not read every word in order. Start with the first ten seconds — that is the hook — then search for the names and terms that auto captions usually miss. Merge captions that split a phrase, split lines that are too long, and close gaps that make text flash.
| Check | Why it matters |
|---|---|
| Names and brands | Speech models default to common spellings. |
| Numbers and units | “15” vs “50” changes the meaning. |
| Sentence breaks | A caption split mid-phrase is harder to read. |
| Filler words | Remove “um” and repeated words unless they are part of the style. |
Step 3 — Style for the destination
For TikTok, Reels and Shorts, set 9:16 and keep captions inside the safe area. For YouTube and course players, 16:9 with a simple, high-contrast style usually reads better. A background or outline is not decoration; it is what makes captions legible over busy footage.
Step 4 — Export
Export a captioned MP4 when the platform ignores subtitle files or most viewers watch on mute. Download SRT/VTT when the platform manages captions (YouTube, an LMS, a video player) and you want viewers to be able to toggle them. Subtitle files are free on every AutoCaptions plan.
Common mistakes
- Captioning before the final cut. Timing drifts after every trim.
- Skipping the hook. The first caption is the one most likely to be wrong and most likely to matter.
- Using a style that hides the subject. Captions should sit in the negative space, not over the face.
- Publishing without a review pass. Machine captions are a draft, not a compliance certificate.
FAQ
How long does it take to add auto captions?
A short clip usually takes a few minutes: transcription plus a review pass. Longer videos take longer to review, not longer to upload, because the video never leaves your browser.
Do I need to edit the captions?
Yes, if the video is going public. Auto captions usually miss names, jargon, accents and crosstalk. A quick pass over the first minute and the technical terms saves embarrassment.
Should I burn captions in or upload SRT?
Use SRT/VTT when the platform lets viewers toggle captions. Burn in for short-form social, ads and any feed where viewers watch on mute.