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Sized for every feed, checked before you post
Say where you’ll post and the slide size, the caption limit and the writer all follow. Switch platform and every slide re-flows. Then Preview shows the post as people will see it, with a checklist that catches the usual mistakes.
One carousel, sized for each feed
Click the platform chip at the top of the editor (“LinkedIn · 4:5”) to open “Where will you post it?”. Pick the app, then a size: the recommended one has a dot. Changing either re-flows every slide, as one undo step.
What each platform gets in aiCarousels
| Platform | Sizes (recommended first) | Per post | Caption limit | How it’s posted |
|---|---|---|---|---|
| 4:5, or 1:1 | A document (PDF) people swipe | 3,000 | Post to LinkedIn, or upload the PDF as a document | |
| 3:4, 4:5, 1:1, or 9:16 for Stories and Reels | Up to 20 slides | 2,200 | Download PNGs, post them in Instagram | |
| TikTok | 9:16 only (photo mode) | Up to 35 photos; the AI makes up to 20 slides | 4,000 | Download PNGs, post them in the TikTok app |
| X | 4:5, or 1:1 | 4 images | 280 | Download PNGs, post in groups of four |
| Threads | 4:5, or 1:1 | Up to 20 images | 500, shown in full | Download PNGs, post them in Threads |
The size you pick on Home is remembered for the next carousel, and the writer, the slide limit and the caption limit follow the platform from the start. On X the AI makes up to four slides, since X shows four images per post; you can add more in the editor and post them in groups of four.
Need the exact pixel sizes, or want to check a file made somewhere else? The free size checkers do that for LinkedIn, Instagram and TikTok.
Carousels
LinkedIn, Instagram, TikTok, X and Threads, at the size that fills each feed.
Image posts
One picture for LinkedIn, Instagram, X or Threads. See image posts.
Text posts
LinkedIn 3,000 characters, X 280 per post, Threads 500, each with its own preview. See text posts.
Video posts
9:16 MP4s for Reels, TikTok and Shorts, and any carousel as a swipe video. See video posts.
Captions
One caption per project, counted against each platform’s limit, with the “…more” cut drawn in.
Downloads
A PDF for LinkedIn, PNG images for the other apps, in full quality on every plan.
Words where the buttons aren’t
On TikTok, Reels and Stories the app’s buttons and captions sit on top of your slide. Turn on safe zones and you see exactly where.
Show safe zones
It is in the same “Where will you post it?” window. It draws the parts of the slide that the app’s buttons and captions cover, so you can keep your words clear. Turn it off to see the clean slide. It is never drawn in your downloads or in the slide tray.
On TikTok and Instagram at 9:16, the checklist reminds you that the edges are covered, with a Show them button. To check a video or a picture made somewhere else, use the free TikTok or Instagram safe zone checkers.
See the post before anyone else does
Click the play icon at the top right of the editor, or press P. Your real slides, your name and photo, and your caption, cut where the app cuts it.
- 01
Pick the platform tab
One tab per platform: LinkedIn, Instagram, TikTok, X and Threads. LinkedIn shows a document post with its pages side by side; Instagram a feed post; TikTok photo mode, full screen; X images side by side; Threads a thread post.
- 02
Read it like your audience
Switch Desktop and Phone (LinkedIn and X) and Light and Dark. Turn the slides with the arrow keys or a swipe. The caption is cut where the app shows “…more”: about three lines on LinkedIn, two on Instagram and TikTok, 280 characters on X, and none on Threads.
- 03
Fix what the checklist flags, then download
Most checks have a button that fixes the problem or takes you to it: Use 4:5, Shorten it, Write it, Add one. Viewing another app’s tab? The button reads, for example, Switch to Instagram and download, and resizes the carousel to that app’s recommended size.
The mistakes it catches for you
Under the caption, and in Preview, the checklist marks each item green, yellow or red for the platform you are on. Red items block the download until they are fixed.
A long first slide
“First slide: N words. Short hooks get read.” Twelve words or fewer is the goal; Shorten it asks your writer to tighten it.
The wrong size
A size that doesn’t fill the most of the feed, with a button to switch to the recommended one.
Text too small
Text boxes too small for their words, or text too small to read on a phone screen. See how big slide text should be.
The caption
Missing (Write it), too long for the app (blocks the post), or a first line cut by “…more”.
Too many hashtags
More than 30 on Instagram or 10 on TikTok: “3-5 good ones work better”.
No question at the end
A tip with an Add one button: your writer adds a closing question to invite comments.
Too many slides, Pro layouts, empty spots
- Slide count. If you have more slides than the app shows in one post, it says so and suggests posting them in groups or cutting some.
- Your name. If the slides still say “Your name”, Add your name opens your signature.
- Empty picture spots. An empty spot would download as a blank tile, so you get Add a picture.
- Pro layouts or a Pro theme without Pro. You can try them in the editor as long as you like; downloading with them needs Pro.
For words that don’t fit their box, smart text fit offers Shorten to fit before anything is checked.
Frequently asked questions
Can I resize a carousel for another platform?
Yes. Click the platform chip at the top of the editor, pick the app and the size, and every slide re-flows. It is one undo step, so you can go back.
Which sizes does aiCarousels offer?
LinkedIn 4:5 or 1:1; Instagram 3:4, 4:5, 1:1 or 9:16; TikTok 9:16; X 4:5 or 1:1; Threads 4:5 or 1:1. The recommended size for each app is marked with a dot.
Are the safe zones in my download?
No. Safe zones are only drawn in the editor, to show where the app’s buttons sit. Downloads and the slide tray show the clean slide.
Is the preview exactly what my followers will see?
It uses your real slides, your name and photo, and your caption cut where the app cuts it. Likes and comment counts are sample filler, and every app re-compresses uploads a little.
What happens if my caption is too long?
The counter turns red and the checklist shows a blocking line, for example “Caption: 2,214 characters, Instagram takes 2,200”. Shorten it, or use the Rewrite menu’s Shorter.
Why does X only get four slides?
X shows up to four images per post, so the AI makes up to four slides for X. Add more in the editor if you like and post them in groups of four.
