You take a photo you like, post it, and the top of your head is gone. Or it goes up as a story and the caption sits across your chin. The photo was fine; the shape was wrong for where it ended up.
Aspect ratios are the dullest part of photography and one of the few things that quietly ruin good pictures. There are four worth knowing, and one shooting habit that covers all of them.
Here is what each ratio is for, and how to shoot once instead of four times.
The four ratios and what each is for
A ratio is a shape, not a size. Square is 1:1, the safe cross-platform shape: tidy in a profile grid and postable almost anywhere without a crop.
4:5 is a portrait rectangle, the tallest shape a feed post is allowed to be. 9:16 is the full-screen vertical shape used by stories and reels, considerably taller again. 16:9 is landscape, the shape of a television or a laptop screen.
If you know which of the four a photo is headed for before you take it, the framing takes care of itself.
Why 4:5 takes more screen than square
A feed is a vertical scroll, and the height of a post decides how much of the screen it fills as it passes. A 4:5 photo is taller than a square one at the same width, so it occupies more of the phone while it is in view.
That is the whole argument for 4:5 in a feed. The argument against it is the grid on your profile, where posts are shown as squares, so a 4:5 photo gets centre-cropped there. If the subject sits near the top or bottom edge, it will be trimmed in the grid even though the post itself is fine.
Stories and reels: the parts of 9:16 you cannot use
A story or reel fills the whole screen, but you do not get the whole screen to work with. The top holds the profile row and the progress bars. The bottom holds the caption, the reply box and the action buttons, and reels add more.
Treat a band at the top and a deeper band at the bottom as occupied. Keep faces, text and anything you need read out of those bands, and centre the important part vertically. The exact size of those areas changes with app updates and with phone screen shapes, so leave more margin than looks necessary rather than measuring it once and trusting the number.
16:9 and where it still belongs
Landscape suits screens you are not holding vertically: a video thumbnail, a website header, anything viewed on a computer or television.
In a phone feed it is the weakest choice, because a wide photo occupies a thin band of a tall screen. Export it when the photo is genuinely about a wide scene, or when the destination is not a phone feed.
Shoot once, then crop: leave room on every side
Cropping in is possible. Cropping out is not. Every one of these shapes is reachable from one photo if you frame with a little air around the subject.
Most iPhones shoot 4:3 by default and offer other ratios in the camera controls, with the exact options depending on the model and iOS version. Shooting at the widest, tallest option gives you the most to cut from. From a vertical 4:3 frame, a 4:5 crop removes a little height, a square crop removes more, and a 9:16 crop removes width from the sides while keeping the full height.
That is why headroom and shoulder room matter: the vertical crops take from the top and bottom, the full-screen crop from the sides, and a tightly framed subject loses something to one of them. Turning on the framing grid while shooting makes this easy to judge, since you can keep the face in the middle band rather than near an edge.
Frame for the tallest crop and the widest crop at once
Before you press the shutter, leave a hand's width of space above your head and a clear gap outside each shoulder. The 1:1 and 4:5 crops eat into the top and bottom, the 9:16 crop eats into the sides, so a photo framed to look perfect in the preview is the one that cannot survive all three. Space around the subject is the margin the other ratios are cut from.
Resolution, compression and why cropping a crop hurts
Instagram displays feed images at around 1080 pixels wide, so exports of 1080 by 1080 for square, 1080 by 1350 for 4:5 and 1080 by 1920 for full screen are the common targets. Uploading something larger is usually fine, since the app resizes down, and resizing down keeps detail far better than stretching up.
What actually damages a photo is repetition. Every upload is re-encoded, so a picture that has been saved, screenshotted, cropped from the screenshot and re-uploaded has been through several rounds of compression, and each round softens edges and blocks up flat areas like sky and skin.
The fix is to keep one edited original and export each ratio from it. Sweet Selfie exports at square, 4:5, 9:16 and 16:9 from the same shot, so the story version is a fresh export rather than a crop of the version you already posted.
Quick answers
What pixel size should I export for Instagram?
1080 pixels on the short side covers the feed: 1080 by 1350 for a 4:5 post, 1080 by 1080 for a square, 1080 by 1920 for a story or reel. Those are display targets rather than fixed rules, and they shift with app updates, so exporting slightly larger is safe.
Does Instagram compress my photos?
Yes, everything is re-encoded on upload. You cannot avoid that, but you can avoid stacking it up: upload a clean export rather than a screenshot, and do not re-download and re-post your own images.
Can I post a 4:5 photo as a story?
Yes, and it will sit in the middle of the screen with bands above and below, usually filled with a blurred copy or a colour. It works, but a proper 9:16 export gives you the full screen and control over what sits behind you.
Which ratio should a profile picture be?
Square, because it is cropped to a circle. Keep the face centred with space around it, since the circular mask trims the corners of the square you upload.
Where to get it
Sweet Selfie: Camera & Editor shoots with a framing grid, then exports the same photo at square, 4:5, 9:16 and 16:9 with no watermark, which is the practical way to get every version from one shot. You can find it on the App Store here: on the App Store
Frame a little loose, and the crops stop being a compromise.
