Instagram Size Checker

Instagram publishes a range, not a size

Every size chart prints a number and leaves you to guess where it came from. The number comes from a published rule. Instagram uploads a photo at the best resolution possible up to a width of 1080 pixels, and keeps a photo at its original resolution when the width is between 320 and 1080 pixels and the aspect ratio is between 1.91:1 and 3:4. At 1080 wide, that is any height from 566 to 1440 pixels.

Two things follow, and both contradict advice you will find elsewhere. Exporting bigger does not buy quality, because 1080 is the ceiling and anything above it is sized down. And 1080 x 1350 is not the tallest option, it is the comfortable one. The ceiling is 3:4, or 1080 x 1440, which most charts still do not list.

What the checker is doing

Drop a file in and the browser reads its width and height off the decoded image, which is why nothing is uploaded and no account is needed. The checker divides width by height, tests the result against the two ends of that range, then checks the width against the 320 and 1080 bounds. If the file is cropped, it draws the cut on your own image so you can see exactly what goes. Ratio is checked first, because Instagram crops to a supported ratio before it resizes: a 4000 pixel wide panorama is a crop problem, not a resize problem, and fixing the resolution would not save it.

When a file falls outside the ratio range, the checker works out what the crop costs and draws it. A 1080 x 1920 story-shaped file in the feed keeps 1440 pixels of its 1920, so it loses a quarter of its height. Instagram centres that crop and lets you drag it, so the choice you get is which quarter goes, not whether one does.

A worked example

A photo straight off an iPhone is 4032 x 3024. Divide those and you get 1.33, comfortably inside the supported range, so nothing is cropped. But 4032 is nearly four times the 1080 ceiling, so Instagram sizes the whole thing down for you. Export it yourself at 1080 x 810 and the resampling happens in your tool, where you can see it.

The full set of dimensions for every surface, feed, carousel, story, reel and reel cover, is in the Instagram post size guide.

Organic posts and ads are not the same spec

This checker is for organic posts, which is what the 1080 ceiling belongs to. Paid creative runs on Meta's ad specs instead, and those ask for larger files: the ads guide recommends 1440 x 1800 for a 4:5 feed image. Both are correct, they describe different pipelines, and mixing them up is how a team ends up exporting ad-sized files for the grid and wondering why nothing looks sharper.