Instagram image size and aspect ratio for posts (2026)

The best Instagram image size in 2026 is 1080 × 1350 pixels (4:5) for a feed post: it is the tallest shape the feed allows, so it takes the most screen. What the Instagram API accepts is wider than that and stricter about the file: a JPEG of up to 8 MB, with a ratio from 4:5 to 1.91:1 and a width between 320 and 1,440 pixels. Everything else, a PNG, a HEIC, a 3:4 photo, a 9:16 poster in the feed, is refused or silently changed. Last checked against Meta's documentation on 8 October 2026.

Two different questions get mixed up in most size guides. "Recommended" is what looks good on a phone. "Accepted" is what the publishing API lets through, and it is the one that decides whether a scheduled post goes out. This page keeps them apart. For text, hashtags and video length see Instagram limits; here it is only about pictures.

Sizes at a glance

Source: Meta's IG User media reference for every row except the pixel recommendations, which are the usual 1080-wide choices that fit those ranges. The ratio check on feed pictures is also enforced by Preflight's own code.

What the API refuses

The publishing API is not the app. Meta's documentation lists these conditions for a feed image, and anything outside them fails or is changed:

• Format. "JPEG is the only image format supported." A PNG, WebP, GIF or HEIC is not a valid image for the API, however well the app takes it from your camera roll. MPO and JPS are named as unsupported too.
• Size. 8 MB at most, for feed pictures, story pictures and Reel covers alike.
• Ratio. "Must be within a 4:5 to 1.91:1 range." A 3:4 photo (0.75) is below 4:5 (0.8) and is out. A 16:9 screenshot (1.78) fits. A 2:1 banner (2.0) does not.
• Width. 320 to 1,440 pixels. This one is forgiving: a narrower picture is scaled up and a wider one is scaled down, so width alone does not fail a post.
• Colour. sRGB; other colour spaces are converted.
• Carousels. Up to 10 items, images, videos or a mix, and Reels cannot be inside one. Meta's guide says carousel images are cropped to the first image, with 1:1 as the default. We found no documented error for a mixed set; the slides are cropped, not refused.
• Where the file lives. The API fetches the picture from a public address at the moment of publishing, so a link that expired or needs a login fails then.

The documentation names no message for a picture that is the wrong ratio or format, only a container whose status ends in ERROR. That is why the failure often shows up hours after you scheduled the post, when the tool finally talks to Instagram, and with little to explain it. Preflight tells you before.

What Preflight does with a picture

Two things happen to a picture, at different moments.

A check before anything is sent. The composer, the REST API and the MCP validate_post tool measure each picture and compare its ratio with the 4:5 to 1.91:1 range, with a hair of tolerance for rounding. A miss is an error that blocks the post and names the measured size, in this form: *Instagram takes feed pictures from 4:5 (portrait) to 1.91:1 (landscape); this is 1080×1440. Crop it first.* Every file in a carousel is checked, up to ten, and the message says which one. Preflight never crops for you, because a crop is an editorial decision. Stories are not ratio-checked, since Meta only recommends 9:16 there.

A JPEG copy at publishing time. When a picture is not a JPEG or is over 8 MB, Preflight makes a copy for Instagram and sends that. The copy is turned upright by its EXIF orientation, scaled so it is no wider than 1,440 pixels (a smaller picture is never enlarged), flattened onto white where it was transparent, and saved as a JPEG at quality 90, or 75 if that is still over 8 MB. A JPEG that already fits is sent as it is, untouched. This runs for single posts, for every slide of a carousel and for stories.

Your original stays as it is. The copy is stored beside the file in your library and removed with it; what you uploaded is never altered, and every other network still gets the original whenever it accepts it. What the conversion cannot do is fix a ratio, so a tall photo still has to be cropped by you.

How to size a picture

Ratio is width divided by height. The three shapes worth remembering:

• 4:5 portrait. 1080 ÷ 1350 = 0.8, exactly the edge of the range. Tallest allowed, biggest in the feed. At the 1,440 px maximum width it is 1440 × 1800.
• 1:1 square. 1080 × 1080 = 1.0. The safe middle, and Meta's default crop for carousel slides.
• 1.91:1 landscape. 1080 ÷ 566 = 1.908, just inside the limit; 1440 × 754 is the same shape at full width. Anything wider, such as 1080 × 540 (2.0), is out.

Worked cases. A phone photo at 3024 × 4032 is 3:4 (0.75), so it fails. Crop to 3024 × 3780 to get 4:5: you remove 252 pixels from the height, then export at 1080 × 1350. A 1920 × 1080 video still is 16:9 (1.78) and goes through as it is, scaled to 1,440 wide if you like. A 1200 × 2000 poster is 0.6, too tall for the feed; post it as a story, or crop it.

For slides in a carousel, pick one ratio and use it for all of them. If the first is 4:5 and the next is 1:1, Meta's guide says the others are cropped to the first, so text near an edge can be lost.

How a picture looks in your profile grid is a separate matter, and one we have not been able to verify. Third-party guides say Instagram has been moving the grid thumbnail from square toward a taller shape, some saying 4:5 and some 3:4, but we found no official Help Center page that states it. Treat it as observed in the app, may change. The safe habit is to keep the subject and any text in the middle of the picture, which survives a square, a 4:5 or a 3:4 crop alike.

Check a picture without an account

The video and image checker reads a picture's type, size and pixel dimensions in your browser, sends only those few numbers and shows a pass or a refusal for Instagram and eleven other networks. To see how your caption will fold under the picture, use the caption preview. The same checks run inside Preflight on every post, on the free plan too (see pricing). The API reference is in the documentation and the posting endpoint in the posts docs.

For the wider picture: the Instagram scheduler and the Instagram integration show how a post gets published, how Graph API publishing works explains the container steps behind the errors above, and all network limits compares the other networks. Meta's own rules are in its content publishing guide and the IG User media reference.