YouTube Thumbnail Checker
Upload your thumbnail and instantly verify it meets YouTube's technical requirements. Check dimensions, aspect ratio, file size, and format before you upload.
Drop your thumbnail here
or click to browse (JPG, PNG, GIF)
Analysis Results
What This Tool Checks
YouTube has specific technical requirements for custom thumbnails. Uploading a thumbnail that doesn't meet these specs can result in rejection, poor quality, or reduced click-through rates. Our checker validates against YouTube's official guidelines:
Dimensions
- Minimum width: 640 pixels
- Recommended: 1280×720 or 3840×2160
- Aspect ratio: 16:9
File Size
- Mobile upload: Under 2 MB
- Desktop upload: Under 50 MB
- Optimal: 100 KB – 2 MB
Format
- Accepted: JPG, PNG, GIF
- Not accepted: WebP, BMP, HEIC, AVIF
- Recommended: JPG at 85-95% quality
Mobile Readability
- Mobile display: ~168×94 pixels
- Text min size: 80pt in design
- Test: Shrink to 150px wide
Common Thumbnail Rejection Reasons
- Wrong aspect ratio: Anything other than 16:9 for standard videos (or 1:1 for podcasts)
- File too large on mobile: Uploading a 4K PNG from your phone hits the 2 MB limit
- Unsupported format: WebP, AVIF, BMP, or HEIC files are rejected
- Below minimum width: Images narrower than 640 pixels won't be accepted
- Copyright violations: Using trademarked characters or logos without permission
- Community Guidelines: Nudity, hate speech, violence, or harmful content
How to Fix Common Issues
Wrong Aspect Ratio
If your thumbnail isn't 16:9, resize it in any image editor. Common 16:9 dimensions: 1280×720, 1920×1080, 2560×1440, or 3840×2160. Don't just stretch an image — crop it properly to maintain quality.
File Too Large
If your file exceeds 2 MB (for mobile uploads), export as JPG with 85-90% quality. This typically reduces file size by 70-90% compared to PNG while maintaining excellent visual quality. For desktop uploads, you have up to 50 MB of headroom.
Unsupported Format
Convert WebP, HEIC, or AVIF files to JPG or PNG using any image converter. On Mac, open in Preview and Export. On Windows, use Paint or an online converter. Most design tools (Photoshop, Canva, GIMP) export directly to accepted formats.
Skip the Technical Checks Entirely
ThumbnailMaker.ai automatically outputs thumbnails at the correct dimensions, aspect ratio, and file size. No manual resizing, no format conversion — just describe your thumbnail and download.
Generate Perfect Thumbnails