Free YouTube thumbnail checker—upload a local JPG, PNG, GIF, BMP, or WebP file to verify 1280×720 minimum, 16:9 aspect ratio, and 2 MB size with desktop, mobile, and sidebar shelf previews. Does not download videos.
No. YouTube Thumbnail Checker analyzes image files you select from your device. It does not fetch video pages, call YouTube APIs, or download streams. Use YouTube Thumbnail Downloader only when you intentionally need public still frames from a video ID.
YouTube guidance commonly cites 1280×720 pixels as the recommended upload with a 16:9 aspect ratio. This checker flags when width or height falls below that minimum. Larger 16:9 masters are acceptable if file size stays under two megabytes.
The tool compares width divided by height to 1.778 (16÷9) with a two percent tolerance to account for rounding in export tools. Slightly off crops from design apps may fail—resize with Image Resizer to exact 1280×720 when needed.
YouTube upload flows often reject or heavily compress very large thumbnail files. Two megabytes is the commonly cited upper bound for custom thumbnails. If you fail this check, run Image Compressor on a JPEG export before re-testing here.
JPEG, PNG, GIF, BMP, and WebP uploads are accepted. Animated GIFs report dimensions of the first frame via the browser decoder. For smallest file size at quality targets, export JPEG or WebP from your design tool.
Three CSS-width previews approximate desktop home (~320 px), mobile feed (~160 px), and sidebar (~160 px) display widths. They help you judge legibility of text overlays at small sizes—not exact pixel-perfect YouTube rendering. Use them to compare two export candidates side by side before you commit to an A/B test in Studio.
No. Analysis uses createImageBitmap or Image in your browser. Unreleased campaign art and client assets stay local.
Use this checker to validate a file you designed before upload. Use Thumbnail Downloader to retrieve existing public stills from a video URL for reference or competitive review—not as a substitute for preflight checks.