How the YouTube thumbnail preview works
- Add your thumbnail. Choose a file, drag one onto the page or paste it. You can add up to three versions. JPG, PNG and WebP files all open.
- Type your title and channel name. Add the video length too, such as 10:24, so the badge in the corner looks right. Leave any box empty and the preview uses placeholder text.
- Compare the five places. Switch between Home, Search, Sidebar, Mobile and Small, then download the comparison as a PNG to share with your editor or a client.
Everything happens in your browser tab. The image is read from your device and drawn on the page, and nothing is sent to a server.
Where your thumbnail shows up
A thumbnail is never seen at just one size. The same image turns up in several places, and each place gives it a different amount of room. This YouTube thumbnail preview draws five of them, so you can judge the image where people will actually meet it.
- Home. The grid of video cards on a desktop screen: a large image, then the title in up to two lines and the channel name. Open the home view.
- Search. A wide image on the left, with the title, channel name and a line of description on the right. Titles get more room here. See the search view.
- Sidebar. A small image beside a list of suggested videos. At this size fine detail turns to noise quickly. Try the sidebar view.
- Mobile. A full-width card in a phone feed with the title below the image. Check this one if your audience watches on phones: the mobile view.
- Small. The image shrunk to about 168 by 94 pixels. If the main idea still reads at this size, it will probably hold up in most other places. Use the small view.
Turn on Show badge area to see the part of the image that the length badge covers, and switch the preview between light and dark to match the way you watch.
What to check before you publish
YouTube publishes the requirements for custom thumbnails. These are the current values from its help page.
| Setting | Value on the YouTube Help page |
|---|---|
| Resolution | 3840 × 2160 recommended; minimum width 640 pixels |
| Aspect ratio | 16:9 |
| File size from a phone | 2 MB or less |
| File size from a desktop | 50 MB or less |
| Format | JPG or PNG |
Source: YouTube Help, support.google.com/youtube/answer/72431. Checked on 2026-10-25. YouTube can change these limits, so confirm them on the official page before a big upload.
Add an image to the tool and the spec check reads your file against this list and tells you what to do next for each line. The YouTube thumbnail checker page explains every line in more detail.
Why preview a thumbnail and title before you publish
A thumbnail looks one way in your editing software and another in a feed. Looking at it in context catches problems while they are still cheap to fix.
Small images lose detail
Text that is easy to read at full size can turn into a smudge at 168 pixels wide. Step back from the screen, or open the Small view, and ask one question: can I still tell what this video is about?
Titles get cut off
Each place shows a limited number of title lines. When a title runs long, the end is replaced with an ellipsis. Type your title into the tool to see which words survive. If the important word comes last, rewrite the title. The title and thumbnail preview page is built around this.
The length badge covers a corner
Most videos show their length in a dark badge at the bottom right of the image. A face, a logo or the last word of a headline placed there can be hidden. The badge area overlay shows you the spot.
Versions look different side by side
Two images that seem equally good on their own often look different next to each other. Put up to three versions in a row and choose with your eyes open. The YouTube thumbnail tester page starts with two slots ready.
YouTube thumbnail preview FAQ
Is this YouTube thumbnail preview free?
Yes. Every feature is free and you don't need an account. There are no paid plans.
Are my images uploaded anywhere?
No. Your images are opened in your browser and drawn on the page. They are never sent to a server and the site does not save them. Closing the tab clears them.
What size should a YouTube thumbnail be?
YouTube's help page recommends 3840 × 2160 pixels at a 16:9 ratio, with a minimum width of 640 pixels. Files must be JPG or PNG, up to 2 MB when you upload from a phone and up to 50 MB from a desktop. We checked this page on 2026-10-25.
Does a thumbnail look the same on a phone?
It looks similar but not identical. A phone feed shows a full-width image with the title underneath, while the desktop home page shows several cards in a grid. The Mobile view in this tool draws the phone layout, but it is an illustration, so check the real result on your own device after you upload.
How is this different from YouTube's own thumbnail testing?
YouTube's Test & Compare feature measures thumbnails with real viewers after a video is published. This tool works earlier: it shows how your image and title look in the feed so you can choose which versions to publish. The two fit together. For how Test & Compare works, see YouTube's help pages.
Limits of this preview
- The previews are illustrations, not exact copies of YouTube's pages. Real layouts change by device, app version and over time.
- The view counts and dates in the previews are placeholder text.
- The spec check reads your file. It cannot tell you whether a design will perform well.
- The AI thumbnail score button is not a working feature yet.