KNOW WHAT YOU'RE CHECKING
A preview, not a prediction.
Checks reference official YouTube thumbnail guidance. This tool does not predict click-through rate. Layouts are illustrative mockups, not exact replicas or live YouTube tests.
Use this YouTube thumbnail tester to inspect a single image. The desktop, tablet, mobile, search and sidebar previews use a centered 16:9 cover crop. The Shorts preview uses a centered 9:16 crop to reveal possible loss of image content. It does not describe every Shorts surface or guarantee how YouTube will display your image.
Supported files & calculations
JPG, PNG and WebP images are decoded locally. Animated images are not supported. The tool's own safety limits are 25 MiB per file and 40 million pixels. These are not YouTube limits.
Aspect ratio checks compare width × 9 with height × 16. Minimum width checks width ≥ 640. The mobile-video check uses 2,000,000 bytes as a conservative interpretation of YouTube's 2 MB label. Title length counts Unicode code points, including spaces; YouTube's own upload counter remains authoritative.
Image crop warnings use the source and preview aspect ratios. They cannot identify whether cropped pixels contain text. Review the small sidebar preview for readability and use the grid overlay to inspect your focal point. All visual decisions start as “Not reviewed.”
Official guidance & course targets
Checked September 15, 2026: YouTube recommends 3840 × 2160 for video thumbnails, 16:9, and a minimum width of 640 pixels. Mobile video thumbnail uploads are limited to 2 MB. Video titles have a 100-character limit.
The requested 1280 × 720 and 640 × 360 checks are retained as course targets, not current independent official requirements. 640 × 360 is derived from a 640-pixel width at 16:9.
YouTube thumbnail guidance ↗
YouTube title limit ↗
Questions, answered.
Does this yt thumbnail tester upload my image?
No. Decoding, rendering and PNG export happen on your device. Closing or reloading this page discards your image and review.
Can I use it as a YouTube title and thumbnail tester?
Yes. Enter an optional title to see it next to your image. Long titles are visually shortened in the mockups; the input is never silently truncated.
Does a thumbnail tester for YouTube know which design will win?
No. This page checks file properties and provides visual previews. It cannot measure audience response, automatically judge text readability, or decide whether a subject is well composed.