Published September 13, 2026
AI Image Aspect Ratios: Which Size to Use for Each Platform
Before writing your next prompt, get the right size first. An image with the wrong aspect ratio gets cropped or distorted no matter how good it looks artistically.
On This Page
Most AI image generation tools let you set the aspect ratio directly in the prompt or the tool's settings, but many users skip this step and then get surprised when the platform crops an important part of the image. This is a quick reference for the key required sizes on each platform, updated for 2026.
Vertical post (best for reach): 4:5 ratio, 1080×1350 pixels • Square post: 1:1 ratio, 1080×1080 pixels • Story and Reels: 9:16 ratio, 1080×1920 pixels • Horizontal post: 1.91:1 ratio, 1080×566 pixels. If you want one size that works well in most cases, choose vertical 4:5, since it takes up the most space in the feed.
YouTube
Video thumbnail: 16:9 ratio, 1280×720 pixels, max file size 2MB • Channel banner: 16:9 ratio, 2560×1440 pixels, keeping in mind that the safe area visible on all devices is only the center 1546×423 pixels • YouTube Shorts cover: 9:16 ratio, 1080×1920 pixels.
Regular feed post and link shares: roughly 1.91:1 ratio, 1200×630 pixels • Story: 9:16 ratio, 1080×1920 pixels • Page cover photo: 851×315 pixels • Group cover photo: 1640×856 pixels.
Standard Pin: 2:3 ratio, 1000×1500 pixels — the best fit for the platform's algorithm, which favors tall vertical images • Full-screen video pin: 9:16 ratio, 1080×1920 pixels • Board cover photo: at least 800×450 pixels at a 16:9 ratio.
Single-image post: roughly 1200×627 pixels (1.91:1 ratio) • Square post or document content: a 1:1 ratio also works well • Personal profile cover photo: 1584×396 pixels • Company page cover image: 1128×191 pixels.
X (formerly Twitter)
Horizontal tweet image: 16:9 ratio, roughly 1600×900 pixels • Header (cover) image: 1500×500 pixels • Profile picture: 400×400 pixels, displayed as a circle, so keep important elements centered.
A Quick Rule If You Don't Remember All the Numbers
Four ratios cover most cases: 1:1 for general square content, 4:5 for high-performing vertical feed posts, 9:16 for all full-screen content (Stories, Reels, Shorts), and 16:9 for thumbnails and horizontal content like YouTube banners. Request the right ratio directly in your prompt (for example, adding "--ar 4:5" in Midjourney, or setting the ratio in the tool's settings) instead of generating a square image and cropping it manually afterward.
Frequently Asked Questions
What happens if you upload an image with an unsupported aspect ratio?
Most platforms automatically crop the image to fit the closest supported ratio, which can cut off important elements at the edges. It's always better to generate the image at the correct ratio from the start rather than relying on automatic cropping.
Do these sizes change often?
Yes, platforms adjust their recommended sizes from time to time, especially the profile grid shape or ad ratios. It's good practice to check the platform's official help center every few months instead of relying on a size you saved a year or more ago.
Conclusion
Save this reference or come back to it every time you're planning new visual content. Getting the aspect ratio right before generating saves far more time than editing a finished image after publishing, especially if you're reusing the same prompts across multiple platforms as in our guide to ready-made social media image prompts.