YouTube Thumbnail Checker
See how your own thumbnail looks on YouTube before you publish — home feed, search, mobile and “Up next”, in light and dark mode, at real sizes.
Free · No sign-upHow to check your YouTube thumbnail
- 1. Export your thumbnail design from Canva, Photoshop, Figma or any editor as a JPG or PNG, then drop it into the box above. It never leaves your device.
- 2. Type your real video title, channel name and length so the mockups match what viewers will see.
- 3. Read the checks — resolution, 16:9 ratio, file size, format, small-size contrast and clutter — and look at every preview in both ☀️ Light and 🌙 Dark.
- 4. Turn on the safe zones and the squint test. If text sits under the length badge or turns to mush at 168 pixels, fix the design and drop it in again.
- 5. Export a YouTube-ready 16:9 JPG and add it in YouTube Studio → Details → Thumbnail.
What makes a thumbnail read well at small sizes
- Three to five words, big and bold. The title already sits next to the image; the thumbnail only needs a hook.
- One clear subject. A face, product or result that still reads when the whole image is the size of a postage stamp.
- Strong contrast. Light text on a dark area (or the reverse), or an outline/shadow behind the letters. The squint test removes color so you can judge contrast alone.
- Nothing important in the bottom-right corner. The length badge and progress bar cover it on every screen.
- Check dark mode. Many viewers browse YouTube in dark mode, where dark-edged thumbnails can blend into the page.
Need to make the image first? Try the AI Image Generator, resize an existing picture with Resize Image, or read how to create a YouTube thumbnail with AI.
Frequently asked questions
Is the YouTube Thumbnail Checker free?
Yes. It is free, needs no sign-up and has no limits. Check as many thumbnail drafts as you like and export as many JPGs as you need.
Is my thumbnail uploaded anywhere?
No. The image is read and drawn on this device only. GrabCast does not upload it, and the tool does not contact YouTube at all — the previews are mockups built in your browser.
What size should a YouTube thumbnail be?
YouTube's Help Center currently recommends 3840 × 2160 pixels for regular videos, with a minimum width of 640 pixels and a 16:9 aspect ratio, in formats such as JPG or PNG. Files can be up to 2 MB when you upload from the mobile app and up to 50 MB from YouTube Studio on a computer. A 1280 × 720 JPG under 2 MB remains a safe choice that uploads from any device. Your account must be verified to add custom thumbnails.
Why does my text look fine in Photoshop but not on YouTube?
You design at full size, but viewers see the thumbnail at about 360 pixels wide on the home feed and around 168 pixels in the Up next list. Thin fonts, long phrases and low contrast disappear at those sizes. The small previews, the contrast score and the squint test show that problem before you publish.
What are the red and orange safe zones?
The red corner is where YouTube places the video length badge and the red watch-progress bar, so text or a face placed there gets covered. The orange strip marks where Watch later and Add to queue buttons appear when a desktop viewer hovers. Keep the important parts of your design out of both.
Can I check a thumbnail for Shorts?
This checker previews 16:9 thumbnails for regular videos. Shorts use a vertical 9:16 frame in the Shorts feed, so the mockups here will not reflect how a Shorts cover is cropped.