You can now upload videos as long as 15 minutes in the IGTV app itself and 1 hour videos are also allowed to all users if you use the web browser version of Instagram.
IGTV video specs
Here is all the video spec information you need for your IGTV video: File format: MP4
Video length: At least 1 minute long
Maximum video length when uploading on mobile: 15 minutes
Maximum video length when uploading on web: 1 hour
Vertical aspect ratio: 9:16
Horizontal aspect ratio: 16:9
Minimum frame rate: 30 FPS (frames per second)
Minimum resolution: 720 pixels
Maximum file size for videos that are 10 minutes or less: 650MB
Maximum file size for videos up to 60 minutes: 3.6GB.
Cover photo size: 420px by 654px (or 1:1.55 ratio)
Pro tip: You can’t edit your cover photo after you’ve uploaded it, so make sure it’s perfect before you do.