What is Instagram post size?
Instagram post size is the combination of a file's pixel dimensions and its aspect ratio. Dimensions describe width and height, while the ratio describes the shape, such as square, landscape, or portrait. Both affect whether Instagram displays the whole asset or crops it.
The practical answer to "ig post size" depends on the format you are publishing. A feed photo, feed video, Story, and Reel can use different shapes, so one preset should not be applied to every Instagram asset.
For an operator managing several brands, the size question has two parts:
- Will the file fit the intended Instagram format without an unwanted crop?
- Will the publishing workflow send the correct file to the correct account and show it after publishing?
The second question is easy to miss. A correctly sized file can still create a production problem if a scheduler reports success but the post is missing, appears on the wrong account, or uses a different crop than the preview.
Choose dimensions for each Instagram post style
The safest Instagram image dimensions are 1080px by 1350px for portrait feed posts, 1080px by 1080px for square posts, and 1080px by 566px for landscape posts. Adobe Express's Instagram sizing guidance, read October 24, 2026, gives the portrait format a 4:5 aspect ratio, the square format a 1:1 aspect ratio, and the landscape format a 1.91:1 aspect ratio.
Use the format that suits the source asset rather than forcing every image into a square. Portrait is useful when a vertical composition needs more feed space, square is predictable for repeated templates, and landscape preserves a wide photograph or presentation slide.
The main Instagram post sizes are:
- Square: 1080px by 1080px, with a 1:1 aspect ratio.
- Portrait: 1080px by 1350px, with a 4:5 aspect ratio.
- Landscape: 1080px by 566px, with a 1.91:1 aspect ratio.
Keep headlines, faces, product labels, and calls to action away from the outer edge. Instagram may display the asset differently in a grid preview, feed, detail view, or shared placement, so edge-to-edge text is more likely to be cut or obscured. Which shape suits which content is covered in Instagram post types and their limits.
Match video, Stories, and Reels to their formats
Instagram video posts can use the same size range as image posts, while Stories and Reels are designed for full-screen vertical viewing. Adobe Express's sizing guidance, read October 24, 2026, says Instagram video posts can range from a 1.91:1 landscape shape to a 4:5 portrait shape.
For a horizontal video, Adobe Express recommends a 16:9 aspect ratio because that matches the natural recording shape of a phone held sideways. The same guidance says video files should be no larger than 4 GB and that video posts can be up to 60 seconds long. Those limits and format rules can change, so check the current Instagram publishing requirements before building a permanent automation.
Stories and Reels need a separate vertical master. Adobe Express recommends 1080px by 1920px for a full-screen Story, using a 9:16 aspect ratio. A Reel may share that vertical working canvas, but the important production decision is to keep text and controls clear of the top, bottom, and side areas where interface elements can cover the content.
Do not solve a vertical-to-horizontal conversion by simply stretching the file. Crop it deliberately, add a background when the entire frame matters, or create a separate composition for the second format.
Resize the source without losing the intended crop
Resize an Instagram asset by choosing the target ratio first, then scaling or padding the source to fit that shape. Resizing changes the file dimensions; cropping changes what the viewer sees. Treat those as separate decisions.
A reliable preparation sequence is:
- Identify the destination format, such as feed portrait, feed square, landscape video, Story, or Reel.
- Create a canvas with the target width, height, and ratio.
- Place the source asset on that canvas without stretching it.
- Choose a crop, background, or letterbox treatment when the source does not fill the canvas.
- Move important text and faces inward before exporting.
- Open the exported file and inspect the first and last frames for accidental trimming.
Illustrative example: a 4:3 product photograph should not be stretched to fill a portrait feed canvas. Place it on a portrait canvas, select the crop that keeps the product visible, and check the exported preview at feed size. If the product label is clipped, change the crop or add a background before scheduling.
Keep the original master file separate from the Instagram derivative. That lets you create a second crop for Stories or another network without repeatedly degrading the source; the ratios each network expects are compared in aspect ratios that prevent crops on every network.
Check the asset before connecting automation
A preflight check should happen before a file enters a multi-account publishing workflow. The check is not just about pixels. It should confirm that the asset, destination account, caption, timing, and intended format belong together.
Use this short preflight checklist:
- Confirm the selected Instagram account and brand.
- Confirm that the asset is the final export, not a draft or thumbnail.
- Confirm the intended post format and crop.
- Check that text remains readable on the smallest expected preview.
- Check that the caption and call to action match the selected brand.
- Record the asset filename or internal reference for later verification.
Fail the check when the visual preview is wrong, the account is ambiguous, or the source file has been replaced after approval. Do not rely on a filename alone when several clients use similar campaign names. A review step that names the account and shows the actual asset prevents a size problem from becoming a brand or delivery problem.
Verify that the published post is actually visible
A publishing confirmation is not the same as proof that the post is visible on the intended Instagram account. Delivery verification should check the destination account, the final media, the caption, and the public or account-level location where the post should appear.
Use this verification sequence after publishing:
- Open the intended Instagram account, not just the scheduler's activity log.
- Confirm that the new post or video appears in the expected location.
- Compare the visible crop with the approved preview.
- Check the caption and media pairing.
- Record the result as visible, missing, or needs review.
- If the post is missing or wrong, pause any retry until you know whether the first attempt partially succeeded.
This last step matters for operators paying per connected channel. An automatic retry can create duplicates when the first attempt was accepted but the confirmation arrived late. A human or agent should distinguish a missing post from a delayed display before sending the same asset again.
Build a format-aware publishing workflow
A format-aware workflow stores the target shape with the asset instead of asking a publisher to infer it from a filename. Useful fields include the destination network, account, post type, crop choice, asset reference, approval state, and verification state.
For developers and AI-agent builders, make the agent choose from approved format labels rather than inventing dimensions in a prompt. The agent can then reject a portrait Story asset assigned to a square feed slot, request a new derivative, or route the item to review. Keep the final decision visible to the operator.
If you publish from a terminal, the limits in posting to Instagram from the command line apply; every route should still use the same preflight and post-publication verification rules.
Choose the right size standard and next step
The best Instagram post size is the one that preserves the subject in the format your audience will see. Use portrait for a vertical feed composition, square for a repeatable grid template, landscape for a wide source, and a separate full-screen vertical master for Stories or Reels.
Do not create one universal export and send it everywhere. Store the original, make a destination-specific derivative, approve the visible crop, and verify the result after publishing. That process is more dependable than treating a successful upload message as the end of the job.
The sizing rules can change, particularly for video limits and supported placements. Keep a current format checklist, label the date of the last review, and update the workflow when Instagram changes its requirements.
Official sources to check
- Adobe Express Instagram sizing guidance (adobe.com)
- Tailwind Instagram image size guide (tailwindapp.com)
Common questions
How do I post a 4:3 image on Instagram?
Upload the 4:3 source only when keeping its original shape is more important than filling the feed. Otherwise, place it on a target Instagram canvas, choose a deliberate crop or background, and inspect the exported preview. Check that the main subject and text remain visible before scheduling the post.
What is the new resolution for Instagram posts?
There is no single new resolution for every Instagram format. Common working targets are 1080px by 1080px for square, 1080px by 1350px for portrait, and 1080px by 566px for landscape. Platform requirements can change, so review the current format guidance before hard-coding an automation.
How do I resize images for Instagram?
Choose the Instagram format first, create a canvas with the target ratio, and fit the source without stretching it. Crop, pad, or add a background when necessary, then move important content inward. Export a derivative, open it independently, and inspect the actual crop before sending it to a scheduler.
What is the best size for an Instagram post in 2026?
For a portrait feed post, use 1080px by 1350px and a 4:5 ratio. Square templates use 1080px by 1080px, while landscape posts use 1080px by 566px. The best choice still depends on the source composition, so select the format that preserves the subject instead of forcing every asset into portrait.
What aspect ratio should an Instagram post use?
Instagram feed posts commonly use a 1:1 square ratio, a 4:5 portrait ratio, or a 1.91:1 landscape ratio. Stories use a 9:16 full-screen vertical ratio. Choose the ratio before resizing, because changing the ratio can remove important parts of the original image.
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