Instagram crops and recompresses pictures that are the wrong shape. These are the pixel dimensions to use for feed posts, stories and reels, and how to resize a photo to match.
Why the size matters
Instagram shows feed images at a width of 1080 px. Anything wider is scaled down, and anything that does not fit an accepted shape is cropped. Preparing the picture yourself means you decide what gets cut, and the upload is not softened by an extra round of resizing.
Sizes for each format
Square post: 1080 × 1080 px (1:1). Portrait post: 1080 × 1350 px (4:5), which takes up the most room in the feed. Landscape post: 1080 × 566 px (1.91:1). Stories and reels: 1080 × 1920 px (9:16). Keep text and faces away from the top and bottom of a story, where the interface overlaps the picture.
Crop to the shape first
Open the Crop Image tool, upload the photo and choose the ratio you need: 1:1 for a square post, 4:5 for a portrait post or 9:16 for a story. Move the box until the subject sits where you want it and apply the crop.
Then resize to 1080 px
Switch to Resize, type 1080 as the width with the aspect ratio locked and apply. The height is calculated for you. Download the result as JPG. Because the picture is already the right shape and size, Instagram has no reason to crop it.
Avoid enlarging small pictures
A photo that is only 600 px wide will look soft when stretched to 1080 px. Start from the largest version you have and size it down. If a small image is all you have, it is usually better to post it as it is than to enlarge it heavily.