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 as a YouTube thumbnail checker for a single image. The YouTube thumbnail preview tool helps you inspect cropping and small-size readability before publishing. 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.”
YouTube requirements & common sizes
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.
1280 × 720 is a common 16:9 preset, not YouTube’s current recommended resolution. At a 640-pixel width, 16:9 corresponds to 640 × 360. These size references do not replace the official requirements.
YouTube thumbnail guidance ↗
YouTube title limit ↗
Questions, answered.
Does this yt thumbnail tester upload my image?
No. The YT thumbnail preview is generated on your device; image decoding, rendering and PNG export happen there too. Closing or reloading this page discards your image and review.
Can I use it as a YouTube title and thumbnail tester?
Yes. The tool places your optional video title beside the image, giving you a YouTube thumbnail and title preview. 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.
After the check
Ready for an audience experiment rather than a visual preview? Read the YouTube thumbnail A/B test guide and its watch-time example.
Image settled? Pick a font for the title in the local font preview →
Checking the video file itself, not just the image? Open the video dimensions guide →
Making a Short? See the YouTube Shorts dimensions guide →
Thumbnail not showing, not updating or blurry? Use the thumbnail troubleshooting guide →
Need a channel watermark for your videos? Make one with the YouTube watermark maker →
Making a cover from anime or illustrated character art? Use the anime thumbnail tool →
Posting an Instagram Story instead? Read Instagram Story size and where the safe-zone guides disagree →
Who makes ThumbGlance and how the facts are checked: about ThumbGlance →
Need a layout to start from? See 10 thumbnail ideas checked at real display size →
ThumbGlance