Grab the thumbnail files of any YouTube video, then drop in your own design and watch how much of it is left at the sizes YouTube shows it.
Get a video’s thumbnail
Check your own thumbnail
Drag across your headline or face to mark it. The dashed box follows it into every size below.
Put it next to other videos
Save
Feed cards are illustrations, not real YouTube screens. Slot widths are approximate because YouTube does not publish them; set your own in the width field. The duration badge is drawn at a fixed illustrative size. Spec checks follow YouTube Help, checked September 27, 2026. Thumbnails of other videos belong to their owners: use them for comparison, not for republishing.
The link box at the top accepts every common shape of YouTube address: a watch page, a youtu.be short link, a Shorts or embed URL, or the bare 11-character ID. It asks the image server for the five standard files, from 1280 × 720 down to 120 × 90, and lists only the ones that really came back. Plenty of older or low-resolution uploads have no 1280 × 720 file at all, and a list with a grey placeholder in that slot would suggest otherwise. Each file can be opened, downloaded, or sent straight into the checker with Use in check.
Format and spec check
The four format buttons change what your image is measured against. Video expects 16:9 and at least 640 px of width, with 3840 × 2160 now recommended; Shorts expects 9:16 and at least 640 px of height, recommended at 2160 × 3840; podcast playlists take a 1:1 square. The size row reads the real file size of an image you drop in, because the limit depends on where you upload from: 50 MB from a computer, 2 MB for a video thumbnail sent from a phone. A 2.6 MB JPG at 1280 × 720 passes on desktop, fails from the phone app, and sits below the new 4K recommendation, and the list says each of those separately.
Marking the part that has to survive
Drag a box around the headline or the face on the large preview. That box is the only thing the tool reasons about: it does not try to find text or faces by itself, so the result depends on what you mark rather than on a guess. The strip of slot buttons on the right redraws the same card at the width of each place, and the table under it turns the mark into numbers. A 3840 × 2160 thumbnail with a 216 px headline keeps a 20 px line in a 360 px mobile card, 18 px in a 320 px desktop card, and 9.5 px in the 168 px suggested sidebar, where the whole image is shown at 4.4% of its size.
The yellow patch in the lower-right corner of the large preview is where the duration badge lands at the selected slot width. It is an illustration drawn at one fixed size in screen pixels, so it covers a larger share of a smaller card. For the headline above, placed in the lower right, the badge column shows Clear in the mobile card, Partly covered at 320 px with 3% of the box under it, and Partly covered in the sidebar with 63% of it gone. Blur, with its own strength slider, and Grayscale change only how you look at the image, which is often enough to see whether the composition still reads without its fine detail or its color. Crop only blacks out everything the selected slot cuts away, so a square or 9:16 slot shows exactly what is left.
Vertical videos and podcasts
Vertical video is its own mode because YouTube Help states that a vertical video with a 16:9 custom thumbnail gets an auto-generated 4:5 image on the mobile home, Explore and Subscriptions pages, while the custom one stays in the watch feed, history and non-mobile apps. The first slot in this mode therefore shows no part of your thumbnail. The tool cannot know which frame YouTube will pick, so instead of inventing one it lets you load a frame you exported from your own video and see how that frame sits in the 4:5 slot. In Podcast mode a 16:9 file is cropped to a square from the centre, and the Crop column shows how much of your marked area is still inside: a title placed along the left edge of the image keeps only 20% of its box.
The field and saving
The lower panel places your card among up to five videos from your niche, at the same width as the slot you picked. You can also add their thumbnails as image files, which keeps the color comparison available even when the image server blocks it. Shuffle moves your card to a new position, and Outline mine removes the highlight so you can look for it the way a viewer would. When the image server allows reading pixels, the tool adds three plain comparisons in brightness, saturation and main color, such as darker than 3 of 4 neighbors; when it does not, the comparison stays visual and the page says so. Save image with marks exports your thumbnail with the marked box and the badge area drawn on it, and the crop button saves the centred 9:16, 1:1 or 4:5 cut as a starting point for the separate file that format needs.