An aspect ratio is simply width compared with height. 9:16 means the picture is 9 units wide for every 16 units tall - the shape of a phone held upright. The pixel size is how many pixels fit in that shape. Instagram currently works with an image width of 1080 pixels for most formats, so the heights follow from the ratio.
The sizes at a glance
| Format | Ratio | Pixels |
|---|---|---|
| Story, reel | 9:16 | 1080 × 1920 |
| Portrait post | 4:5 | 1080 × 1350 |
| Tall portrait post | 3:4 | 1080 × 1440 |
| Square post | 1:1 | 1080 × 1080 |
| Landscape post | 1.91:1 | 1080 × 566 |
Instagram adjusts its formats from time to time, so it is worth checking the official help pages if something looks off. The ratios above have been stable for a while; 3:4 is the most recent addition.
Stories and reels: 9:16
A story fills the phone screen, so 9:16 is the only shape that uses it fully. Anything else gets bars or a blurred background around it.
The catch is that the screen is not all yours. At the top sit the progress bar, your profile picture and name. At the bottom sit the reply field and the buttons. A widely used rule of thumb is to keep text and faces out of roughly the top and bottom 250 pixels of a 1920-pixel story. Reels are more crowded still, with the caption, audio name and buttons stacked up the right-hand side and along the bottom.
In practice: keep the title a little below the top, and do not place anything important in the lowest part of the frame.
Feed posts: 4:5, 3:4 or 1:1
For feed posts, taller takes up more of the screen as people scroll, which is why portrait 4:5 became the default choice for photographers and brands. A square post is a smaller thumbnail in the feed; a landscape post is smaller still.
In early 2025 Instagram changed the profile grid from square thumbnails to taller 3:4 ones, and began accepting 3:4 uploads for the feed. That affects how posts look on your profile page:
- A 3:4 post appears in the grid uncropped.
- A 4:5 post is trimmed slightly at the sides in the grid.
- A square post is trimmed noticeably at the sides.
If you care about how the profile looks as a whole, keep important content, especially text, away from the left and right edges of square and 4:5 posts.
Carousels: the first slide decides
A carousel can hold up to 20 photos or videos. All of them are shown at the same shape, and that shape is set by the first slide. If the first slide is 4:5 and a later one is square, the later one is cropped or padded to fit.
The simple rule is to export the whole carousel in one shape. If your photos come in different orientations, crop them to the same ratio before you post, so you decide what gets cut rather than Instagram.
Which shape to choose
- Posting a story or a reel: 9:16, with text inside the safe area.
- Posting to the feed and want the most space: 4:5, or 3:4 if you care most about the profile grid.
- Posting a carousel of mixed photos: 4:5 for all slides is the safe default.
- Cross-posting: 9:16 also suits TikTok, YouTube Shorts and Facebook stories; 1:1 is still the most widely accepted shape across other networks.
Why exporting at the right size matters
If you upload a picture larger than Instagram needs, it gets scaled down and recompressed, which can soften fine detail and small text. Exporting at the target size in the target shape gives you control over how the final image looks, rather than leaving the decision to the upload.
The same goes for text. A title placed for a 9:16 story will not land in the same place if the slide is later cropped to 4:5. When a story needs to go out in more than one shape, lay out each shape separately rather than cropping one into the other.