Create a custom thumbnail for an instagram video by designing a 1080x1080 square image and adding it to the front of your video. When you post the video on IG, the 1080 by 1080 thumbnail will flash at the beginning of the video and will be the frame that shows up on your Instagram feed. Use this free tool to crop your cover image to the right maximum size for your Instagram feed. For tips on adding it to your Instagram videos, check out this Instagram thumbnails article .