Meta ads in the editor
Single image or video. Up to 5 headlines at 40 characters, 5 descriptions at 25, and 5 primary texts at 125. Placements the preview knows include Facebook feed and Instagram feed. The ad can carry an image, or a video you upload (MP4, MOV, or WebM, up to 100 MB), a public Google Drive or Dropbox link, or a YouTube link.
Carousel. Up to 10 cards. Each card has a headline at 40 and a description at 25. The ad has up to 5 primary texts at 125. A carousel card video takes a YouTube link only.
Story or reel. Up to 5 primary texts at 125, on a 9:16 frame, shown as a Facebook story or an Instagram reel. Headline and description counts are zero on that format. It takes an image or the same video upload or link as a single ad.
Where the full primary text shows
The live preview shows primary text the way the Meta feed does. On the Facebook and Instagram mobile feeds, and on carousels, it stops after three lines, with See more on Facebook and more on Instagram. That label is not a button.
To read a single image or video ad's primary text in full on the ad, pick Facebook above the live preview, then the desktop icon. The Facebook desktop feed shows all 125 characters.
To read every primary text in full on any Meta format, open the Preview tab, next to Editor at the top of the editor. It lists each line of copy in full, with its character count. A client who opens your share link starts on that tab, unless the link is set to Editor, a Studio feature, which opens on Editor.
Story and reel previews keep the primary text to a few lines on the 9:16 frame.
Call-to-action labels in the editor include Shop Now, Learn More, Sign Up, Download, Contact Us, Book Now, Get Offer, Apply Now, Subscribe, and Watch More. The default is Shop Now.
None of the Meta formats are marked exportable. The editor does not hand you a file Meta will import.
Meta's ads guide is at https://www.facebook.com/business/ads-guide. Re-read it when this note is older than 90 days. The editor's counter wins for what you can type here.