For years any and all photos we've uploaded to Instagram have been forced into a 1:1 square aspect ratio. We've lost arms, heads, fronts, backs, tops, and bottoms, all the the crop. Well, no longer. Now Instagram supports portrait and landscape aspect ratios for both photos and video. No black or white bars needed. Here's how!
Note: Instagram neglected to mention that the aspect ratio feature won't simply appear by downloading the app. It's "rolling out" over time. So, if you don't see the button, don't panic. Check back in a few hours or days and hopefully it'll be there. You can try restarting Instagram or rebooting your iPhone, but patience is your best bet. (Hopefully Instagram will be clearer about the nature of their updates in the future.)
How to post landscape or portrait pictures or videos to Instagram
Pictures and video default to the square aspect ratio when you first select them but you can no easily adjust them from there.
Launch Instagram from your Home screen.
Tap on the Open Camera button.
Choose your photo or videos.
Tap on the full size button overlay at the bottom left of the photo. (Or simply pinch and zoom out.)
Tap Next to continue on.
You can now add filters and effects, same as always, and post and share your instas when you're done.