Captions for Instagram Reels, with AI
Mid-screen, clear of what Instagram covers, with the spoken word in yellow. On your PC, no watermark.
Updated: October 2026 · 6 min read
To add captions to a Reel for free with AI on your PC: install AppGrabbit, open Download › Subtitles with AI, paste the Reel's link or drop the mp4 and click Get subtitles. Pick Center on a real frame (free): it sits mid-screen, away from the bottom 35 % Instagram covers, with the spoken word in yellow. Make the video leaves you the MP4 with no watermark. 1 credit · burning: Pro
Reel, Story or feed: three sizes, one rule
On Instagram the same video can go to three places, and the interface covers something different in each. The rule: where there is interface on top, the text goes mid-screen; where there is none, it can go at the bottom.
| Reel | Story | Square video in the feed | |
|---|---|---|---|
| Size | 9:16 · 1080×1920 | 9:16 · 1080×1920 | 1:1 · 1080×1080 |
| What Instagram covers | ✗ Bottom 35 %, top 14 %, sides 6 % | ✗ Top and bottom | ✓ Nothing over the video |
| Style that fits | ✓ Center | ✓ Center | ✓ Classic or Box |
| Comes out of the app as | ✓ 1080×1920 | ✓ 1080×1920 | ✓ 1080×1080 |
Instagram's captions, and when they are not enough
When you post a Reel, Instagram generates automatic captions and whoever watches can show or hide them from the video itself. For accessibility they are good. But you do not choose them: not the style, not the size, not where they go. And they stay on Instagram: if you save the Reel to post it on TikTok or YouTube, or send it on WhatsApp, it travels without them. Burned-in subtitles stick to the video, with the spoken word lit up, and they are what makes a muted viewer stay. The honest part: burned-in ones cannot be hidden or translated afterwards.
For a Reel watched muted
- The first three words — should already be on screen: the Center style shows three or four at a time and the one being said turns yellow.
- Mid-screen — not at the bottom: the bottom is your description and the audio.
- A title on top — if you come from an audio (voice note, podcast), the audio-to-video guide adds the title and bars that follow your voice.
- Time — a 51-second Reel burns in about 9 seconds with an NVIDIA card.
Step by step
- 1Install AppGrabbit for Windows — Download the free installer (everything included). Windows will say it protected your PC because the installer is not code-signed: click More info, then Run anyway.
- 2Bring the Reel in — If it is already posted, paste the Reel's link and the app downloads it in full. If you just shot it, drop the mp4 from your phone. A square video for the feed works too.
- 3Click “Get subtitles” (1 credit) — The first time, the app gets the AI engine ready on your PC (a one-time download) and carries on by itself. Out come the .srt, the .vtt and the .txt in the Subtitles folder, timed word by word.
- 4Center for the Reel, Classic for the feed — In a Reel or a Story, Center: mid-screen, away from the bottom 35 % Instagram covers. In a square feed video there is no interface on top: there, Classic at the bottom reads fine.
- 5Click “Make the video” (Pro or the 7-day pass) — The subtitles are burned into the video, at its size and with no watermark. The MP4 is named after your video plus “_subtitulos” and lands in the Library.
- 6Post it where it goes — Reel or Story: 1080×1920. Square feed: 1080×1080. H.264 with AAC audio, what Instagram asks for. The MP4 sits in the Subtitles folder and in the Library.
Frequently asked questions
Instagram generates them when you post and viewers can show or hide them from the Reel. Good for accessibility, but they live on Instagram, you do not pick a style, and they do not travel with the file if you save it or post it to TikTok or YouTube. Burned-in ones stick to the video.
At the bottom, the account name, the description and the audio: close to 35 % of the height. At the top, 14 %; on the sides, 6 %. Center is drawn mid-screen and stays clear; Classic and Box move up 15 % from the bottom, which on Reels is still inside what gets covered.
Same 9:16 and the interface also covers the top and the bottom. Center stays safe.
If your video is 1:1, the subtitles keep their size and the MP4 comes out 1080×1080. In the feed there is no interface over the video, so there Classic at the bottom reads without trouble.
The app downloads it, but captioning and reposting another person's video without permission is a bad idea. Use it with your videos or ones you are allowed to use.
Getting the subtitles (.srt, .vtt and .txt) costs 1 credit; Free comes with 5 a month. Previewing them on your video, in the three styles, is free. Burning them in (“Make the video”) is for Pro (USD 8.99 a month) or the 7-day pass (USD 3.99, no renewal). There is never a watermark, not even on Free.
Nothing. The video stays on your PC: the AI engine (Whisper, whisper.cpp) runs on your computer, on your NVIDIA card if you have one or on the CPU if not, and FFmpeg burns the subtitles right there.
Source for what Instagram covers: TikTok, Instagram and Facebook safe zones (House of Marketers)
Related guides
Captions for your Reel, on your PC
Windows 10/11 · Get subtitles: 1 credit, 5 free a month · Make the video: Pro or 7-day pass