Quick answer: make YouTube thumbnails 1280 × 720 pixels, a 16:9 ratio, with a minimum width of 640 pixels. With an AI image tool, generate at 16:9 (for Midjourney, add --ar 16:9), then resize to 1280 × 720 and add your text in an editor.
The specs
| Setting |
Value |
| Recommended size |
1280 × 720 pixels |
| Aspect ratio |
16:9 |
| Minimum width |
640 pixels |
| Common formats |
JPG, PNG |
YouTube can limit file size and may require account verification before you can upload custom thumbnails. Check YouTube's help pages for the current requirements.
Generating a thumbnail with AI
- Set the ratio to 16:9. In Midjourney, end your prompt with --ar 16:9. In other tools, choose the 16:9 or "landscape" option.
- Prompt for a clear subject and space for text. For example: "close-up of a chef tasting soup, bright kitchen, shallow depth of field, empty space on the right side". Asking for empty space makes adding a title easier.
- Generate large enough. If your tool lets you choose, go bigger than 1280 pixels wide, such as 2048 × 1152, then scale down. The AI image aspect ratio calculator gives exact sizes that keep 16:9.
- Resize to 1280 × 720 and add text in an image editor. AI image tools still get text wrong surprisingly often, so add it yourself.
Design tips that matter
Design for a small screen. Most viewers see your thumbnail on a phone, often only a couple of centimetres wide. Shrink your design to that size before you publish.
Three to five words, maximum. Large, bold text with strong contrast. Use a thick outline or a solid background behind it.
Keep the bottom-right clear. YouTube puts the video's length there.
One focal point. A face showing an emotion, or a single clear object, reads better than a busy scene.
Match the video. Thumbnails that misrepresent a video can hurt viewer trust and watch time.
Common mistakes
- Generating square and cropping. You lose a large part of the image. Generate at 16:9 from the start.
- Tiny text. It's unreadable at phone size.
- Low resolution. A 640 × 360 image technically works but looks soft on large screens.
- Unlicensed images. Use images you made or have the rights to use, and avoid recognisable people, logos or characters you don't have permission for.
For sizes on other platforms, see social media image sizes for 2026, and for the --ar parameter, Midjourney aspect ratios explained.
Converting other sizes to 16:9
| If your image is |
Do this |
| 1920 × 1080 |
Scale to 1280 × 720, same ratio |
| 2048 × 1152 (AI output at 16:9) |
Scale to 1280 × 720 |
| 1024 × 1024 (square) |
Crop to 1024 × 576, then scale up, or regenerate at 16:9 |
| 1080 × 1920 (vertical) |
Regenerate; a 16:9 crop keeps only a small strip |
The AI image aspect ratio calculator shows exact 16:9 sizes for any width.
A simple thumbnail layout
A reliable layout for most videos:
- Left two-thirds: the subject, such as a face, product or result, large and well lit.
- Right third: three to five words of text in a bold, high-contrast font.
- Bottom right: left clear for the video length badge.
- Background: simple and uncluttered, ideally a colour that contrasts with the subject.
Mirror it if your subject faces the other way. Faces looking toward the text tend to draw the eye to it.
Prompting for a thumbnail background
AI image tools are good at backgrounds and subjects but unreliable with text. A prompt pattern that works well:
[subject], [setting], [lighting], bold colours, simple uncluttered background, empty space on the right side, 16:9
Then add the title in an editor where you control the font and spelling.
Test before publishing
- View the thumbnail at about 160 pixels wide, roughly how it appears in phone search results.
- Check it in light and dark YouTube themes.
- Compare it next to other thumbnails for the same topic: yours should stand out, not blend in.
Updating thumbnails later
You can change a thumbnail after publishing. If a video gets impressions but few clicks, a clearer thumbnail is one of the simplest things to test.
Thumbnail checklist
- 1280 × 720 pixels, 16:9.
- One clear subject, large and well lit.
- Three to five words of text at most, high contrast.
- Bottom-right corner kept clear for the length badge.
- Readable at thumbnail size on a phone.
- Honest: it matches what the video delivers.
- Uses images you have the rights to.
PNG keeps text and sharp edges crisp, while JPG keeps photo-heavy thumbnails smaller. If YouTube rejects a file, reduce its size by exporting as JPG at slightly lower quality rather than shrinking the pixel dimensions.
Sources and further reading
Figures in this guide were calculated with our own calculators and checked against these sources.