If you are one of those Instagram users who cares about the dimension of their Instagram stories, below guide with help you through. https://instazood.com/blog/what-are-the-instagram-story-dimensions/
• You should keep the 9:16 aspect ratio for your stories.
• The high-definition resolution of an Instagram story is 1080 x 1920 pixels.
• Lowering the resolution while maintaining the aspect ratio in pixels (900 x 1600 or 720 x1280), will make your story buffer faster on the viewer’s device.
• Do not reduce resolution to less than 600 x 1067 or the quality is considerably lost.
• Maximum Image Size: 30 MB
• Maximum video Size: 4 GB