How the First Slide Sets the Instagram Carousel Size for Every Slide

What is the Instagram carousel size?

Meta sets the Instagram carousel size from the first slide, cropping every image in the post to that slide's aspect ratio, and the Content Publishing API accepts ratios from 4:5 portrait to 1.91:1 landscape. At the 1080-pixel width Instagram's help centre names as its upload width, that range runs from 1080 x 1350 down to 1080 x 566 pixels. Pick one ratio, build every slide at it, and put the slide that defines the frame first.

The rule comes from a single line in Meta's Content Publishing guide, under the carousel Limitations list: "Carousel images are all cropped based on the first image in the carousel, with the default being a 1:1 aspect ratio." The Instagram Help Centre says the same thing from the app side: "the orientation you choose (square, portrait or landscape) affects all of the photos or videos in your post. You can't select a different orientation for each photo or video."

So a carousel has one size. Slide two through slide ten inherit whatever frame slide one sets, and anything outside that frame gets cut.

What pixel sizes should each carousel slide be?

Each carousel slide should be 1080 pixels wide, with a height that matches the one ratio you chose for the whole post. Meta's help centre says Instagram uploads photos "up to a width of 1080 pixels", keeps photos between 320 and 1080 pixels wide at their original resolution, and sizes anything wider down to 1080. Exporting at 1080 wide means Instagram does no resizing on the width.

Shape	Ratio	Pixels at 1080 wide	App	API
Square	1:1	1080 x 1080	Yes	Yes
Portrait	4:5	1080 x 1350	Yes	Yes
Tall portrait	3:4	1080 x 1440	Yes	No
Landscape	1.91:1	1080 x 566	Yes	Yes

The app column comes from the help centre article on image resolution, which accepts ratios "between 1.91:1 and 3:4 (a width of 1080 pixels with a height between 566 and 1440 pixels)". The API column comes from the Image Specifications block in Meta's IG User Media reference: "Aspect ratio: Must be within a 4:5 to 1.91:1 range."

The square row is the safe default. It is the ratio Meta names as the carousel default, and it sits inside both the app range and the API range. Portrait 4:5 takes more vertical space in the feed and is the tallest ratio a scheduled carousel can use.

Why does the API reject a 3:4 carousel the app accepts?

A 3:4 slide falls outside the range Meta's API documents, because 3:4 is taller than 4:5. Written as width divided by height, 4:5 is 0.8 and 3:4 is 0.75. The API's floor is 0.8, so a 1080 x 1440 image clears the help centre's limits and fails the developer reference.

The two Meta pages also disagree on width. The help centre sizes photos down to 1080 pixels wide. The IG User Media reference lists "Minimum width: 320 (will be scaled up to the minimum if necessary)" and "Maximum width: 1440 (will be scaled down to the maximum if necessary)". Neither page mentions the other's number.

For a carousel you plan to schedule, that leaves one practical rule. Design at 1080 pixels wide and stay between 4:5 and 1.91:1. A 1080-wide file sits inside both width ranges, and a 4:5 to 1.91:1 ratio sits inside both ratio ranges. The single-photo version of the same specs is in our guide to Instagram image size, and the error codes the API returns for each broken rule are covered in Meta's Instagram API image requirements.

What happens when carousel slides have different aspect ratios?

Slides with different aspect ratios lose their edges, because Instagram crops each one to the frame set by the first slide. In the app you get a chance to fix it: the help centre says "To adjust how each photo or video is cropped, click and hold it, then drag to adjust how it fits in the frame." Through the API there is no such step, and Meta's guide says only that the images are "all cropped based on the first image."

Here is what that looks like with a mixed set:

1. Slide one is a 1080 x 1350 portrait product shot, so the frame is 4:5.
2. Slide two is a 1080 x 566 landscape banner. To fill a 4:5 frame, its sides get cut, and text near the left and right edges disappears.
3. Slide three is a 1080 x 1080 square. It loses a strip from each side too, since 1:1 is wider than 4:5.

Reverse the order and the damage flips. A landscape first slide sets a 1.91:1 frame, and every portrait slide after it loses its top and bottom. Meta's guide does not say which part of a mismatched image it keeps, so do not count on a centred crop. Text near an edge is the first thing to go, which is one more reason the advice in our post on text overlays on Instagram carousels keeps copy away from the borders.

The fix is to resize before upload, not after. Bring every slide to the same ratio in your design tool, add a solid background behind any image that does not fit, and export the set together.

One frame for every slide

Mixed ratios

• Slide one is a 4:5 portrait, so the frame is 4:5
• The 1.91:1 banner loses its sides
• The 1:1 square loses a strip from each side
• Text near the edges disappears

One ratio

• Pick one ratio before you design
• Resize every slide in your design tool
• Add a solid background behind images that do not fit
• Export the whole set together

Is the Instagram carousel size the same for videos?

Video slides follow the same frame in the app, and Meta's API documentation publishes no separate size spec for video inside a carousel. The help centre's orientation sentence covers "all of the photos or videos in your post", so a video in an app carousel takes the square, portrait or landscape frame you chose.

The developer docs are thinner. The cropping line in the Content Publishing guide names "carousel images" only. The IG User Media reference lists specs for images, Reels, Reels covers, Story images and Story video, and has no section for carousel video. It does rule out Reels: carousel items must be built as image or video containers, "(reels are not supported)". That means the Reels picture size, which allows ratios from 0.01:1 to 10:1 and recommends 9:16, does not describe a carousel video.

The safe approach is to treat a video slide like an image slide. Export it at the same ratio as the rest of the carousel, and do not upload a 9:16 clip into a 4:5 carousel expecting it to keep its full height.

How big is a seamless panorama carousel?

A seamless panorama carousel is one wide image cut into slides of equal size, so its total width is the slide width times the number of slides. Every slide still has to match the single carousel frame, so the panorama's height equals one slide's height.

Slides	Square slices (1:1)	Portrait slices (4:5)
2	2160 x 1080	2160 x 1350
3	3240 x 1080	3240 x 1350
5	5400 x 1080	5400 x 1350
10	10800 x 1080	10800 x 1350

Ten is the ceiling for a scheduled carousel. Meta's API guide says "Carousels are limited to 10 images, videos, or a mix of the two", while the help centre allows up to 20 when you post from the app. Each slice is its own file, so each one has to stay under the 8 MB maximum in the IG User Media reference.

Where AdaptlyPost fits

AdaptlyPost publishes Instagram carousels of 2 to 10 items through Meta's API, so the 4:5 to 1.91:1 range above is the one that applies. The Instagram posting API page lists the carousel rules for developers. AdaptlyPost does not resize uploaded media, so upload each slide at the size Instagram requires, with 8 MB the ceiling on any one file. A carousel that includes a video can go to Instagram, Threads and Telegram, and nowhere else in the same post. To build a panorama, AdaptlyPost's free Instagram carousel splitter cuts one image into 2 to 10 slides. The Instagram scheduling tool queues carousels alongside feed posts, Reels and Stories, and our guide to scheduling carousel posts on Instagram and Facebook walks through the upload step by step.

For what a carousel post is and when to pick one over a single image, start there before you settle on a size.

Frequently asked questions

What size should an Instagram carousel be?

Make every slide 1080 pixels wide at one shared ratio: 1080 x 1080 for square, 1080 x 1350 for 4:5 portrait, or 1080 x 566 for 1.91:1 landscape. Meta crops all slides to the first slide's frame, so a single ratio across the set keeps every edge.

Does the first image decide the carousel's aspect ratio?

Yes. Meta's Content Publishing guide says "Carousel images are all cropped based on the first image in the carousel, with the default being a 1:1 aspect ratio." The Instagram Help Centre adds that the orientation you choose in the app applies to every photo and video in the post.

Can you mix portrait and landscape slides in one Instagram carousel?

You can upload them, but Instagram shows them all in one frame. The slides that do not match the first slide's ratio get cropped, and Meta's API documents no parameter to adjust that crop. Resize every slide to the same ratio before you upload.

What is the tallest Instagram carousel size?

The tallest ratio the Instagram app accepts is 3:4, or 1080 x 1440 pixels. Through Meta's API, which schedulers use, the tallest is 4:5, or 1080 x 1350, because the IG User Media reference requires a ratio between 4:5 and 1.91:1.

Do carousel videos follow the same size rules as Reels?

No. Meta's IG User Media reference says Reels cannot be carousel items, so the Reels spec of up to 10:1 with 9:16 recommended does not apply. Meta publishes no separate size spec for carousel video, and the help centre says the chosen orientation applies to videos too, so export video slides at the carousel's ratio.

Does AdaptlyPost resize carousel images to fit Instagram?

No. AdaptlyPost does not resize uploaded media, so each slide has to arrive at the size and format Instagram requires. Build all slides at one ratio between 4:5 and 1.91:1 and keep each file under 8 MB.

How many slides can an Instagram carousel have?

Through Meta's API, a carousel is limited to 10 images, videos, or a mix of the two. The Instagram help centre allows up to 20 when you post from the app. A scheduled carousel therefore tops out at 10 slides, and AdaptlyPost publishes carousels of 2 to 10 items.

What is the default aspect ratio of an Instagram carousel?

Meta names 1:1 as the default, which is 1080 x 1080 pixels at the 1080-pixel width. The first slide can change that frame, and every other slide is cropped to match. Square also sits inside both the app range and the API range, so it is the safe choice.

Why does my 3:4 carousel fail when I schedule it?

The Instagram app accepts 3:4, but Meta's API requires a ratio between 4:5 and 1.91:1. Written as width divided by height, 3:4 is 0.75 and the API floor is 0.8. Re-export the slides at 1080 x 1350 and they fit.

What is the maximum file size for an Instagram carousel slide?

Meta's IG User Media reference sets the maximum at 8 MB per image file. Each slide is its own file, so a panorama cut into 10 slices needs every slice under 8 MB. AdaptlyPost does not resize uploaded media, so check file sizes before you upload.