AI images for YouTube: thumbnails, scenes, banners and profile pictures

Sizes that work, how to prompt for each use, and the mistakes that make AI visuals look cheap.

The sizes

• Thumbnail: 1280×720 px, 16:9. Keep the file small (JPG or PNG). Big subject, few elements, readable on a phone.
• Channel banner: 2560×1440 px. Only the center area of about 1546×423 px is visible on every device, so put names and key visuals there.
• Profile picture: square, shown as a circle and very small. Simple icon, high contrast, no small text.
• Scene images: 16:9 for long-form, 9:16 for Shorts.

How to prompt

A good image prompt names subject, setting, light, camera/style and mood, in that order. Example: "Close-up of an old sailor reading a letter, inside a dim ship cabin, warm candle light from the left, cinematic 35mm photo, quiet and emotional."

For thumbnails add: one clear focal point, high contrast, empty space for text. Add the text later or keep it to 2–4 words.

Keep it consistent

Reuse the same style words for every scene of a video, and keep a short "style sheet" for the channel. Viewers recognize a channel by its look long before they read the name.

Mistakes that look cheap

• Too many elements in one thumbnail.
• Distorted hands, faces or text that nobody checked.
• Changing art styles from scene to scene.
• Images that show something the video never delivers. That kills trust and retention.

Checklist

• Thumbnail 1280×720, readable on a phone
• Banner content inside the center safe area
• One style sheet for the whole channel
• Every image checked for errors before upload

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