The problem with instagram is obviously, everything viewed is in a portrait aspect ratio. Mostly likely you created your video in a 16 by 9 or 21 by 9 widescreen aspect ratio. Basically the opposite.
You have three viable options here. One, upload your video in the widescreen format that you shot it in and have a lot of people scroll right past your video because it takes up such a small amount of space on people’s phones.
Two, create a portrait aspect ratio and scale your video up so it fills that entire frame. While this is good because it uses a lot of real estate in the instagram app when people are scrolling their feed, your video that was carefully composed is now zoomed in a crazy amount and ruins your intended shot composition. Yes you can play around with what is seen in the shot by adjusting horizontally, but that takes time, and it still doesn’t show the shot as you intended.
So here’s what you should do in my opinion. In whatever editing software you’re using, create your project dimensions to be 1080 by 1350. You’ll take the part of your video that you want to upload (I usually don’t upload more than 40 seconds because I want to give the viewer just a taste of the video), and you’ll put it on that portrait aspect ratio timeline. Next we’ll duplicate that clip, scale it up by 300% or so, and add a Gaussian blur on it. It’s up to you how much you want to blur it. I choose to blur it quite a lot so it’s not entirely distracting. It’s important to note, if you’re video is 21 by 9 you’ll need to add a custom black generator to simulate a letterbox effect and to give some space between your video and the background.
The reason this export setting is the best is because not only does it KEEP your video the way you created it, perfect composition and all, but it also takes up the MAXIMUM amount of space on Instagram, so when people are scrolling, your video will take up their screen, catch their eye, and pull them into viewing your video. In my opinion it hands downs beats the zoomed in portrait upload style and the teeny tiny widescreen ratio style. Basically it’s the best of both worlds.